Cult of Undeath with Fantasy Hack

This may seem like an unusual topic, if you know the history of both (although, of course, I don't presume that anyone pays that much attention.)  Let me give a very quick and dirty summary of my system development, though.

1. I'd been running around house-ruling d20 Modern and D&D 3.5 to be used with my DARK•HERITAGE setting for years.  I'd also played with other systems, but never really settled on anything.  Until...
2. In early 2013 I belatedly discovered the Microlite system (amazingly, by then it had already been around for almost 7 years!)
3. In May of 2013, I created my own adaptation of m20 for use with DARK•HERITAGE.  I also took the two existing Star Wars iterations of m20, combined them into a single one, and added my own elements.  I think this was a great adaptation of the m20 rules to an existing setting that works well with the premise of an old-fashioned game like m20 anyway.  Even if it's just me saying so.
4. These systems underwent periodic revision and fixing of minor elements for some time.  Most of these changes were minor, but they didn't really completely settle down until 2015, at which point both the Star Wars m20 and DARK•HERITAGE m20 were considered complete.
5. Also in 2015, I was confronted with the possibility of needing to pick up where our group had left off; in a campaign that was faltering.  We ended up doing something else (Call of Cthulhu—a campaign that also ended up faltering, as it happens.)  I decided to start the CULT OF UNDEATH project; a thorough pruning and adaptation of Paizo's Carrion Crown adventure path.  For whatever reason, I decided to adapt m20 to do this.  This was the genesis of the m20 CULT OF UNDEATH game; I basically took the DARK•HERITAGE game and replaced the DARK•HERITAGE races with some that more closely resemble standard D&D.  I could, of course, simply have used an existing m20 D&D version, including the original 2006 m20, or maybe the Purest Essence.  But, for whatever reason, I wanted to do my own thing.  
6. In June of 2016, I decided to expand the CULT OF UNDEATH system into a full-blown "My D&D"—i.e., my own take on what I think the D&D system should look like to best emulate my ideal game of it.  This became, of course, FANTASY HACK.

So, the question is weird and unusual; because CULT OF UNDEATH is the seed from which FANTASY HACK grew; mostly by adding the appendices, examples of play text, and bulking up the monster list, rather than by changing anything fundamentally.  Of course you can run CULT OF UNDEATH with FANTASY HACK when they are the same game.  But what I really mean is, are there elements in FANTASY HACK that maybe shouldn't be used in CULT OF UNDEATH?

I think the expansion of the monster list to include a lot of classical mythological creatures is a moot point to some degree because in running any type of published adventure, you're using the monsters preselected for you.  But at the same time, I've included many of them on the random monster tables, and Timischburg is now absolutely fit to be used in a hexcrawly fashion as the PCs travel from one location to another.  Also; I've specifically included a Typhon daemon (based on the Greek mythological Typhon—loosely, anyway) as part of the CULT OF UNDEATH summary.  Use anything on the monster list as you see fit.  It shouldn't be a problem.

Appendix II adds a lot of material, and here's where we need to really get to brass tacks.  I think using anything out of the class-builder system in Appendix II would be fine.  I think using the black powder firearms would be fine too—maybe even desirable to give the whole thing a kind of Solomon Kane or other vague Witchunter vibe to it.

So the real brass tacks; the real thing where the GM might need to step up and "Just say no", is in the Appendix II races.  The race selection for CULT OF UNDEATH was specifically selected not only to feel like classic D&D, but to also work with the implied setting that CULT OF UNDEATH comes with.  Sure, sure—I actually created a setting for it; a bowdlerized version of Ustalav, really—but still, the question is begged.  Some of the races of FANTASY HACK may not fit all that well.   Let's go through them with a bit of discussion, shall we?

• Goblin.  In a place like Timischburg, goblins would struggle to fit.  They wouldn't be welcome by the citizens or the militias either one.  They'd be constantly mistrusted.  Not really appropriate to be used, in my opinion.  Don't.
• Jann.  The jann could conceivably come from one of the port cities on the coast, but they'd otherwise be so exotic that that'd be a distraction everywhere that they went.  I'd probably say no.
• Kemlings.  No, I don't think so.  As exotic as the jann and yet as mistrusted as the goblins if anyone actually knows their provenance.  Too much trouble to try and make them fit, I think. 
• Nephilim.  These would also be distracting, but they're less obviously weird—I can see them.  No doubt about it, nephilim would be so rare anywhere that they go, in any setting that doesn't specifically account for a number of them, that they'd have problems standing out. This would be true in other areas besides Timischburg, if there were any. But that's part of what the race means, I suppose.
• Woses.  My first thought was to say no, since the earliest version of the Haunted Forest was that it was "haunted" by fiercely territorial and angry woses.  They'd be seen as enemies; like an orc trying to travel peacefully in Third Age Gondor.  It just didn't make any sense.  But then, I thought about it and decided that actually there probably are populations of woses in Timischburg, since the Bitterwood is pretty much a werewolf forest.  The woses could be the descendants of werewolves that lost the potency of their curse after many generations.  They actually fit quite well. This begs the question; what do I really want to do with the Haunted Forest, then?  Maybe it shouldn't be haunted by woses after all, it should be "haunted" by something else altogether.  It's not a major issue, because the CULT OF UNDEATH doesn't send anyone up to the Haunted Forest, unless of course the PCs just decide to go exploring up there.  I'll probably eventually define Timischburg so well that it could be a complete hexcrawl, but for now, let's just assume that the Haunted Forest is more like southern Mirkwood, and the Necromancer of Dol Guldur—serial numbers filed off first, of course—is up there somewhere.
• Other Races.  I used these rules to create a few more races for EBERRON REMIXED, and a few of them would fit.  Half-elves, gnomes, warforged, changelings, kalashtar, and hobgoblins.  The half-elves and gnomes would—I guess—fit as well as any of the regular D&D races in the main rules would.  I wouldn't otherwise allow any race-building, unless it's just mechanical reskinning, with a cosmetic adherence to a more common race.
• All that said; if goblins and hobgoblins don't fit, why exactly do orcs fit?  Just because the core rules allow half-orcs, and I make no mechanical distinction between orcs and half-orcs, really.  If you want to disallow orcs, do so with my blessing.  If, on the other hand, you want to presume that Timischburg does harbor some small populations of "savage humanoids" and orcs are in, then I suppose you can go ahead and add goblins and hobgoblins as an option too.  

Although, of course, I've gotta be full disclosure honest and transparent.  The population of Timischburg as I envision it is about: 85% human (Tarushan ethnicity make up most of these; a kind of Eastern European Romanian, but with a pseudo-Austrian Timischer aristocracy super-imposed over the top.)  Cursed make up about 7%, especially in the Ubyr and Orlock counties, reaching their highest density at Inganok.  Woses make up another 7%, especially in the rural areas between the Bitterwood and the Black River, and south of the Haunted Forest, where they are most common.  Only 1% of the population is anything else.  So, for "maximum verisimilitude" quite honestly the standard D&D races of elfs, dwarfs and halflings are too exotic to do anything except stand out and be a distraction—they're only included to make this whole thing feel more like the D&D source material from which it's adapted.  This is a very humano-centric setting (as are all of the settings I dabble with) and honestly, Cursed and Woses are just humans with a curse on their bloodlines anyway.

Those population numbers don't include monsters, though—including undead.  The dirty secret that's not so secret is that some of the Timischer nobility are actually vampires.  There are other undead floating around, of course.  Plenty of haunted spots and ghost stories that happened to a friend of a friend are more commonly told in Timischburg than anywhere else.  And, sadly, all too many of them turn out to be true.

Ghouls haunt the graveyards at night.  Byakhees flit around the towers of reclusive rural lords with vile reputations.  Dark Young lurk in the depths of the Haunted Forest, and werewolves have famously made the Bitterwood dangerous to pass through.  Succubi siphon the life from urban socialites who fool with powers over their heads that they don't understand or respect.  The Eltdown Fens crawl with shambling, moss-covered skeletons that rest uneasily in their watery graves.  The coastline features mysterious areas that are rumored to be ancient ports destroyed by Ketos.  Liches keep lonely towers in the wilderness, surrounded by their rotting servitors.  Nightgaunts haunt the peaks of the Knifetop Mountains.  Dark rumors of shoggoths lurking in the sewers of Grozavest and Preszov continue to linger.  The Thursewood is crawling with thurses (duh.)  The hilly ridge that gradually rises to the Mountains of Mittermarkt are topped with lonely, old barrows where wights lurk in the night.

Etc. and so forth.  Everyone likes to talk about how during the Middle Ages people rarely traveled more than a few miles from where they were born.  With a place like Timischburg, it is painfully obvious why that's actually a great idea.