Short answer yes they are drops for escha nms so it helps that, reive's are personal pool and TH doesn't usually help or coffers (though for incursion it will help the quality and number of coffers dropped to you in a personal pool) but I've never seen conclusive evidence it doesn't help reives just it probably doesn't.
Long answer, it would be truly exhaustive work to list all the places TH works and doesn't so I'll just give you the rules for when it will or won't help you.
TH Full Power:
* Crafting materials from direct mob drops (Think spider web from spiders to vulcanite ore from Escha Zi'tah t3 monsters) with a chance to double it.
* Items from monsters that drop directly, with a few rare exceptions for "set drop slot" items like defending ring and pixie earring sharing the same guaranteed drop slot and can't double drop ever.
* VW drop rates even though they are coffers, it raises alignment across the board by a small amount, 1% for each level of TH.
TH Mid Power:
* Getting double drop chance (and greater double drop chance the higher the TH value) off monsters that have a 100% drop chance. Examples of this is almost all gear in Escha, Vagary Bosses, Mulcibar's Scoria from PW, and Umbral Marrow from SL. TH is helping your chance of a second item rather than just a first item as well as maybe a second one. Escha zones will sometimes double drop with no THF around, because they have blessings for TH and people have TH augs from rare dark matter augs or chaac belts but all that caps at 4. THF caps at 14 (though should be pretty content with 11-12 most the time) and higher TH does help double drops occur most often and may even affect which items have what rate to drop to some degree (but that'd be hard to prove and is speculation). More examples of this are mats guaranteed to drop, but can up number and quality like eschalixir, airlixir, skirmish stones/weapons, and reisenjima augment stones/sacks as well as delve item drops (which can be exchanged for copper vouchers).
* BCNM double drops for mats and items if there is no coffer, like most rem's tale chapter 6-9 fights.
TH has no effect:
* What is in opened coffers, like rem's tale chapter 1-5 fights.
* With the exception of incursion, what drops in your personal pool. There's speculation it can help what drops in your personal pool in escha, which isn't guaranteed and effected by the spoils vorseal, and I seem to remember some dev post about it but don't remember if he confirmed or denied for now tho listing as has no effect.
* Key items, though I speculate it does work for red proc key items in abyssea if you didn't proc, you still have a chance to get it, just not 100% TH seems to affect that rate.
* As far as it's known, it has zero affect on sinister reign.
* No affect on Unity coffers.
Unknown:
* Not sure if it affects reives personal drops but I'm pretty sure it doesn't as I've never ended up with more HP bayld or anything than the guaranteed 1 (or 2 or 4 depending on campaign).
* Not sure if it affects domain invasion drops either but I'm guessing not since they are delivered to a personal pool.
TH is still and probably will never be fully understood, unless the devs want to cough up info on it which they've repeatidly said they do not wish to do, though they did finally confirm on the behemoth defending ring thing.