A relatively less intrusive but more hacky solution could be to give the move two secondaries that both apply the condition and make one of them dustproof. We could use onRestart to detect if the condition is applied twice to the same mon, and if it has been, run the function to cure burns on all afflicted targets.

I think this is the best option. I actually find it pretty weird that we don't track which Pokémon were hit by a move. Once implemented, it's not intrusive at all.

This solution also fixes https://www.smogon.com/forums/threads/bug-report-mechanics.3760740/

I should have fixed the Magician bug in a separate PR, but since it uses the same solution—move.hitTargets—and I don't know when this PR will be merged, I decided to fix it here instead.