Wow, sounds like you've read a lot in that space of time
I haven't got time to write a full answer at the moment, but basically Angel appearing out of that portal in Season 8 isn't meant to be right after ATF or anything.
As for when it does occur, god knows. Thats one of my main gripes about Season 8/9, that there has still been no explanation or anything of how Angel became Twilight *really* (apart from about one page in the Riley one shot where he's talking to Whistler about it)
It was just like-
Comic- "Who is Twilight.... it's Angel!"
Reader- "oh right, so how did that happen?"
Comic- "erm, anyway..."
I still say their should have been a mini of the Angel we know in his time in LA, like the end of IDW run, with Connor, Gunn, Illyria etc, and then slowly how he became this masked "supervillain" if you will.