I suppose if you kill something, and its warp core breach damages another hostile ship nearby, that damage could be attributed to you. I don't know the internals of the STO combat log, or the ACT plugin.
I've never noticed anything weird with MaxHit myself. As to whether it's 'relevant', it's interesting to see big crits, but what matters (IMO) is sustained damage per second.
Thanks for the link.
I've always thought that something in ACT was causing it to miss report MaxHit and give credit to me for something else. When I'm looking at that column I usually just scroll down until I see damage I know came from me. I'll have to click on that line and see if I can see more detail.