the main issue is whether to give the Tarlok FTL. IIRC they don't have any in the official book, instead relying on just (un-statted) sublight ships, giving them a fairly small empire located within one (rather abundantly inhabited) solar system.for robotech though, you'll probably want a larger empire for them, with some worlds/outposts located in systems other than the one solar system, so some form of FTL might be worthwhile.
i'd say not Fold drives though. perhaps whatever slower FTL the Tyrolians used prior to inventing fold drives/discovering protoculture instead? something on par with say, the Alien unlimited galaxy guide for speeds, where a lightyear takes months if your slow, weeks if your fast? (instead of being able to cross hundreds of them in a day like with fold drives, going by show evidence)
you could use the AUGG to make their ships going that way, actually, once you decide how to convert them to MDC. the result would be ships with better sublight speeds (robotech ships barely accelerate a third of a mach a melee, but AUGG ships do a flat 1 mach per), but much much slower FTL speeds. which could make for an interesting dynamic.
in re-reading, the Charizolon solar system gives me a feel comparable to the
12 colonies of Kobol from BSG or
'the verse' from Firefly in terms of system size and habitable real estate. if you keep it as the book has it with one large system, you might want to consider turning it into a binary, or trinary solar system and add a few additional stars to it, to spread the inhabited worlds out a touch more and add the uninhabited/uninhabitable worlds you'd expect from a solar system. to be honest, as currently written it practically screams "engineered system", hinting at some ancient race of "first ones" having terraformed every world in the system to habitability, and perhaps having planted all those races. a multi-star system probably would give off similar vibes, but not to the same obvious extent. the possibility of the system having been engineered could be an interesting mystery if you want to go that route. you'll want to figure out why it was though, even if you never tell the players. an experiment of some sort? or maybe a race of 'lifebringers' akin to the First ones of babylon 5 or the
'progenitors" of star trek, which seeded life everywhere they could just because they could. or perhaps even something like the
Forerunners of Halo, which fall a bit into both categories, being both nurturers and seeders of life, and experimenters on it.
if you go the route of an engineered solar system, this would give you an opening for "ancient artifacts" as a plot-hook/device.. perhaps the Tarlok found a ancient star ship in the system's asteroid belt or crashed on one of the worlds, and are rebuilding it into a terrible super-weapon flagship (reminiscent of the SDF-1 on earth). or found some other piece of hyper advanced technology and are trying to weaponize it.
another issue from the skraypers setting to bring up.. the Atlantis connection. the inhabitants of Seeron are (heavily implied to be) descendants of true atlanteans, probably ones that took a bit of a backwards timeskip in the process of dimensionally traveling to the world. if you keep that connection it opens up a few interesting threads. first, did Atlantis exist on robotech earth in its history, or are they dimensional refugee's? second, would this make the Tirolians and the praxians offshoots of true atlanteans too? (certainly an interesting idea) if humanity discovers this connection, what wil lthe UEEF think of it?
and perhaps a bit more left field.. there are other groups in the palladium game library also implied to be conencted to atlantis, liek the 'atlantees' from mechanoids. which might give you another gameline to mix in.. the alien races of the later mechanoids books, and the various star systems from the whole mechnoids trilogy, could thus be scattered into the setting to fill some gaps. perhaps as minor worlds in the tirolian empire or other bordering star nations. though the age of the mechanoids books might make converting them to robotech's more modern ruleset tricky. the mechanoids themselves, at least have their rifts sourcegbook 2 versions for use, though they might be a bit much to add. (though it might allow a bit of a battlestar galactica feel.. especially if the 'atlantees' of the machanoids are changed to be ancient seeronians or the ancestors of tirolians..) alternately you could just drop the psychic cyborg aspects of the mechanoids and mine their material to give the Haydonites a wider variety of android forms and mecha.