In regards to the Bandits they are hirelings by that noble woman as we know... and the Vampires need something to feed on... not sure if Gargoyles are blood suckers in this universe... but the bandits likely make for an excellent food supply... and noone will miss them.
The smaller factions in the West are Mahgda and her family, aswell as Vixenatrix and her dragon Clan.
Well we already have Vixenatrix for lizzard fetish.... your children could turn into Dragonkin (scaled humans with dragon features, like claws, fangs and or ears) or Kobolds (more lizzard like)... not sure if a jungle really fits into the climate of the map we have seen so far, certainly would make for an interesting change though
I have 5 things I just wanna talk about:
•the baby Gargoykes look like there trying to suckle in the scenes where there birth is announced so mabey they do feed (blood possibly, not sure myself)
•I know Maghda is planned to have a "special" daughter at some point but I'm not sure she could be classed as a faction, yet. Not sure what's happening there.
•From the way Vixenatrix said it i feel like her daughter (& other children) will all be "pure" dragons with the ability to shift like there mother. Seeing as dragons have been breeding with mortals for so many years I reckon they have the dominant gene. But I see you're point.
•I feel like we may be able to side with Cath, the noble woman (has Tink actualy confirmed she is a noble? Just asking cos theres nothing in game that actualy confirms that she is) but if we side with her mabey we can get some bandit thugs to work for use, like the goblins.
•Climate wise yeah I get that a jungle might not work but I feel like it's a believable transition from the Marshlands. Go with the stereotype fantasy map of "Grim Cold North" & "Savage Hot South".