So, since I want it both production based and to be achieved any time, rather than at end round only, and much prefer it showing clearly in the customizable settings, I'll use this hack of having multiple endrounds, as it doesn't appear causing any troubles (and the game is not meant to ever have any triggers). But I'm open to refactor it if it would be possible to achieve the same result with victory triggers/conditions, eventually.
I guess since we assume multiple endrounds is not intentionally supported, no reasons to document it.
Still, I have to say that personally doesn't like the fact that this endround step manages both hardcoded victories and sets uses for triggers, as they seem unrelated matters, and, in my mind, it should have rather been called "victory" step, doing only that (traditionally as the last step in the sequence).