almost none of the attempts to describe the way factions play are 100% true.
UEF ranks 3rd in shield HP, and their land units at tech 2 and 4 are the squishiest across the board. Percivals are matched by bricks, so they don't stand out.
Cybran land units are slow at T2, loyalists are fast but they're matched by titans so they don't stand out. Cybran being stealthy is true
Aeon doesn't have highly specialized units. It's literally just the absolver
Seraphim is the most vague of them all. They're described to have "multi-purposed units" (what does that even mean?) and highly advanced units? Their mass costs and strength are comparable to other factions, with the small exceptions of the ilshavoh and mobile t3 shield
I would recommend sticking to describing a faction's lore and keeping it at that. It's too hard (impossible?) to give a short and concise gameplay description of each faction that actually fits it