No need to credit me, you and dead have done all the real work. You're welcome though!
The Pandashi necromancer that attacked me in the second year was raising the dead left and right with no issues, so I doubt it's that. More likely it's something wrong with my setup for attempted undead training, or maybe something badger-specific. I'll fiddle with it later once my dorfs get done plugging the volcano and obsidianizing the magma sea around the delicious candy, and my FPS recovers.
I'd say the extreme reluctance to seek medical treatment for badgers can be classified as a racial feature, though with perhaps the addition of better natural healing rates to compensate a bit. It seems to fit their personality, anyway, to simply tough out any injury until it heals or doesn't on its own. The main issue is that currently, it seems as though they aren't healing at all, though they also aren't deteriorating unless they also have an infection. Note that this is all in 42.06, though. I like my DFHack/Gemset/TWBT too much to upgrade to 43.x just yet, the changes to healthcare in the latest versions probably will affect things.
I've since received a petition from a Honey Badgerwoman Scholar to join as a citizen as well, and I'm rechecking her and the dancer periodically. Have yet to see any sign of them being afflicted with the same perpetual tiredness as the mercenaries. Checking Legends shows that the dancer is in fact the child of two abductees, born in a Goblin civilization before leaving to join the performance troupe. However, the scholar was born in a badgerman civilization and only left to join my fortress. I'll see what happens if I toss them into a squad later, though.
Mercenaries never petitioning for citizenship is just the way it works, for whatever reason.
Visitors are predominantly badgermen and tigermen, but that's probably a function of my embark preferences and proximity. So far across 4 fortresses:
Badgers: Mercenaries, Scholars, Entertainer (Troupe member, goblin abductee).
Tigermen: Mercenaries, Scholars.
Pandashi: Mercenaries.
Nagas: Mercenaries, Scholars.
Ferric Elves: Mercenaries, Entertainers (Troupe members, unsure on entity)
Frogmen: Entertainer (Troupe members, unsure on entity)
War Elephants: Mercenaries.
Furies: Mercenaries.
I will note that of the mercenaries, Badgermen and Tigermen have been extremely common across all embarks. Pandashi and Naga appear somewhat less so, but that's likely more a function of embark location, as on two of the four I've gotten enough to fill a squad over the the course of a decade or two. I haven't checked in Legends, but I'd say these four races are sending out native mercenaries. The remaining races have been rare enough that they may have been converted abductees. May have to design a custom pocket world to test each race individually to be sure, but again, lazy.
Oh, and side note. Helmet Snake Women claim nestboxes and lay eggs that can be collected and cooked. Shame Nagas are extremely rare in my current fortress, I want to see if I can set up a breeding experiment.