The torch is a suspect but the custard breaking underneath is not from the flame. Sugar sits on top of a set custard, and torching it for 20 extra seconds at low heat is not enough to push through and curdle the whole thing. What you were probably fighting is an unstable custard base that was on the edge already, so some nights it held and some nights it tipped over, and slowing down your torch just stopped you from overworking it. A grainy, broken custard means it was overcooked in the oven or the eggs got too hot, and no amount of flame control fixes that. The real test would be to torch one the old way, full blast, on a custard you are sure is perfectly set, and see if it actually breaks. If it does not, then the torch was never the problem and you changed two things at once and gave credit to the wrong one.

The "solitaire with extra steps" line is funny but honestly kinda true sometimes, your mileage may vary depending on the group. In my experience the problem is never the game, it is the one person who cannot stop themselves from playing everyone else's turns too. I have been that guy before and I did not even notice until someone called me out, so sometimes just saying "hey let me mess this turn up on my own" works better than you would think. The Crew was a smart move on your part because you literally cannot quarterback a hand you cannot see. Mysterium is hit or miss for me since the ghost can still try to steer everything, but at least it keeps people talking. If the guy keeps doing it after a gentle nudge, I just stop inviting him to co-ops and save him for competitive games where he can only ruin his own night.