Good thing I'm still awake to fix these bugs.
Okay, I've fixed that stuff & re-uploaded, except for the 'quirk' and the puzzling puzzle. Ta ta for now.
For an unfortunate and soon-to-be-rectified reason* the fixing of this bug requires me to change the behaviour of those trees temporarily. For now, only removing one of them will open the gate.
*"All Triggers->16-31" doesn't recognise layered triggers?! Who programmed this thing anyway?