While working on a module I've encountered some weird trigger behavior I figure I'll mention in case it helps someone since it doesn't seem to be documented anywhere.
I began initially with getting all of the interactions working between 2 NPCs. One of the things I wanted to do was have one NPC ask another NPC to follow them to a specific, non-private room. To do this I found that it was sufficient to use ActionAboutRoom on the card making the request during the conversation.
Once I got everything working between NPCs, I found that for some reason this didn't work the same if an NPC asked the PC to follow them. Instead of going to the room set by ActionAboutRoom, the NPC would instead lead the PC to a random room. After a lot of trial and error, and examining other modules, I've found that in order to get the NPC to lead the PC to the correct room, and to have them properly talk to the PC after they both arrive, you have to use SetRoomTarget on both the NPC, and the PC. Initially I tried just using SetRoomTarget on the NPC making the request, and while this caused them to lead the PC to the correct room, once they arrived they would end up just locked in place with the red circle around them, leaving both the NPC and the PC unable to do anything. If you use SetRoomTarget on both cards though, then everything works correctly.
What makes this even more confusing is that SetRoomTarget is labeled in the editor as an "NPC Action", yet you have to use it on both the NPC and PC cards. It also has a comment that says "//Probably doesn't work", which I can understand because it only seems to work if you use it in this very specific manner.