I don't know if i should be posting this here but I encountered a few trolls in my last game. It seemed like there entire mindset was "I can troll here better than normals." It was extremely frustrating. Everyone but me who wasn't trolling left and the game ended a 5v2. Very hard to test when a large portion of players are trolling like that.

I reported them but does the report function work the same way for PBE?

It does

No it doesn't. There is no tribunal system for the pbe server. There is though leaverbuster which works only for queued games.

It's potentially a huge problem... then.

I just had a few trolls, as well =\.

(Let me get invaded level one as a jungler, then yelled at me when I was useless after they stole both my buffs...)

when you get trolls in customs, just remember their summoner names and ban them from future customs.