As of
commit d57ee948c, wherever an Exit's trigger overlaps one or more other object triggers, the Exit will always take priority:
SuperLemmix now has a full "Exit Rules All" physics system; if ever a lemming makes contact with an Exit's trigger by whatever means, and time remains on the clock, they will exit regardless of current state or any other factors.
If anyone playing SuperLemmix notices any situation where exiting can be expected (however remotely) and doesn't happen, please let me know and I'll fix it as soon as possible.