Since this forum is shutting down, I figure I’d mention that BoardGameGeek has a dedicated TI4 forum that’s pretty active.
Base game: https://www.boardgamegeek.com/boardgame/233078/twilight-imperium-fourth-edition/forums/0
Expansion forum: https://www.boardgamegeek.com/boardgameexpansion/315895/twilight-imperium-fourth-edition-prophecy-kings/forums/0