Copyright's just a b*tch, even trying to be creative has it's negative parts, in my opinion, custom troops should be player created orders like in PoP, Michadr has showed interest for this sorta of thing and player created troops trees seems messy even if immersive, in PoP you created your own order bit by bit, not an "whole new faction" I'd say; leave the factions alone and add player made household troops, that ought be a good do-able alternative and somewhat neat.
Oldtimer, some things are hardly logical, and we're in testing stages of Perisno, mentally, you can project the "feel" that the world is hard and unrewarding, there is a lot to do yet, we've just compacted a lot of resources, and made it fit together in this flow we call World of Perisno, to follow the tide is a must, you can make several boats, but if it can't survive waterfalls, they're just useless.
Pragmatic, a prognostic that we must ignore the flaws of the gem until the gemcutter comes to shape it, we can design what form may it so take, but only the gemcutter can maketh it as we desire in his edge of skill.
metaphor: Having the gem, is more important than having a costly masterpiece. In time we might have both.
To have such "plausible consistence", we must have a ground, which we have currently, observing the path Perisno took in the past, from what it is now, that's a sure "feet-on-ground" for us, a playable version, of course, it has flaws, but that's humane feel about it, it is imperfect still, none of the devs are machines fabricating something, they're putting time in Perisno, harken to it, even if some stuff seems outta-place not-here o'there.