You can see your standing in the interaction tab. Supposedly they don’t shoot neutrals like they did before, but maybe they do.
In any case the complete list of all systems Trigs can regularly spawn in is in the appendix to this document:
But I would say that is just the most likely list. It’s not clear yet which rarer wormholes will bring Trigs to Empire space. There probably is always going to be a risk they might show up anywhere, so you might want to make friends with them.