I don’t have any particular knowledge of Fishpig though I’ve seen it in at least one other thread, one of which I think you also participated in: https://theeventscalendar.com/support/forums/topic/event-calendar-pro-doesnt-work-with-fishpig/
In that particular thread I don’t think we determined if it was a compatibility issue with Fishpig or not as there was no further follow-up.
All I can really say is the our plugins are built to work with regular WordPress installations first and foremost: if other platforms/tools can somehow wrap up and integrate WordPress then it’s really their job to resolve any compatibility issues (though we are of course open to any feedback where we might improve compatibility if it can be demonstrated that our plugin is doing something non-standard that is creating an issue).