How to win as Seraphim vs UEF considering the positions are equal and both of you switch to t2 land:
you get T2 + Gun while UEF ACU gets Nano + Gun.
You send your army NOT to your acu but to other frontline where enemy doesn't have ACU either and you abuse the fact that your army is very strong on t2. If enemy acu wants to push you build 1 t2 pd and stand in front of it so that enemy ACU can't kill it. After a while you get 3rd t3 pgen and you can go nano yourself, switch to t3 (UEF switches to t3 as well) and then your ACU + t3 unit composition (Siege tanks, Shield + Snipers) are much better if micro'ed correctly so you can push and win the game by slowly killing his expansions and taking good trades.
Now unless you can provide some specific questions, or situations please stop posting so much cause I feel like you ignore other posts and just try to convince everyone of your truth (spoiler alert it's not like that and TOP 10 players are telling you that) and If that's the case just go somewhere else because then this discussion is pointless.