Thank you! Hope you enjoy it.
I'm not 100 percent sure but you can most likely add a mapflag to the map then remove the mapflag when the treasure boxes are about to be spawned. Since if you add a normal mapflag, the treasure boxes won't drop any items.
After line 250, add this:
setmapflag "+strcharinfo(3)+",mf_nodrop;
After line 379 (which would be line 380 after adding the first one) , add this:
removemapflag "+strcharinfo(3)+",mf_nodrop;
That is untested by the way. I am not 100% sure how the "mapname" field will work considering the map is instanced.
Let me know if it works. I might add it as a feature in a future version.
First one is a lot of work. =P
Second one will prevent the players from getting the treasure drops at the end.