The Arcam unit has massive documentation on its several triggers. I'd say that the difficulty is reading all the details. I'd make a table of what does what when. When I saw that one of those triggers is for sending a signal to tell a display what kind of video signal is being sent, I quit reading. Figuring that out is a job for a consultant (or an A/V installer who has to work with the unit).

I don't think it will matter much what those triggers do, though, until you figure out the Epson. The word "trigger" cannot be found by searching in the Epson file, but there IS a trigger jack on the projector jack panel. But it's labeled TRIGGER OUT, so it won't be of any help to you.

If I'm seeing this right, this projector is a processor + projector kit, though, and this document doesn't say anything about the processor. The two things labeled A and B on the mostly unlabeled drawing of the back of the processor might be trigger inputs. You'll need to find the document on the processor to move ahead.