Honestly, I have... quite a number of faction mods. The Xhan upon second look, have lost everything but the capital. After a few hours of playing in the strike mission and invasion logs, the most common are Persean, Diktat, and tri-tach. Legio never even raided them (and got crushed by me). Hegemony and Ludd have been too busy fighting an eternal crusade against my AI using ass. Guest appearances in raids from the Lanestate, ORA, Junk Yard, Imperium, and Shadowyards (that usually fail).
I don't know anything about starsector modding, how factions work, or how you've coded the faction. But with things like Luna Lib out there, would it be possible to enable the user to adjust settings on the Hiver to give them a little extra boost in a more crowded sector? (Or turn them into the Tyranids)
The idea of a hostile faction gradually encroaching, multiplying to more and more planets, and battering down all the factions is something that def changes up the endgame. But if its a "Lot of work to rework that, you are just using too many factions" situation, that's fine too. Thanks for your work on the mod regardless