It does sound actually better than roundlimit!
Then test activating the mercylimit on vote?

However, having constant mercylimit at 7 sounds a bit dull, not that plz. Sometimes ppl want to keep playing a -7 game.. Comebacks are SWEET!!

For sure dropping the roundlimit sounds the least hackish way here.
That would actually result in the normal game ending with result counted (hopefully) in qlstats etc.

And big thanks for looking into this )

Is score diff of 6 enough of a constraint?
That would leave 0-6 and 1-7 so forth on the table.

Super hard to say how ppl behave before testing and It's mostly about the team anyway, if the forfeit needs a lot of votes from the team.

Some maps would really get easier to vote/play, if the losing team could forfeit the match then the game gets too lopsided.
Maybe the best example of this is overkill, where after things get lopsided the meta changes and play gets eeeextremelyyyy slow, resulting in endless pain for everyone ...