Minor thing. Twilights categorically cannot create Alchemicals.
Only Autochthon and the demiurges he empowers can create Alchemicals, and demiurges must be mortals.
Alchemicals are also no more loyal to Solars than the DBs. Their loyalty is to the Great Maker and to their nation. Considering why Autochthon left in the first place, they're unlikely to just blindly throw in with the Solars either.