Well if the functions are empty you might as well, since they don't do anything anyway. Except 11 because it looks a bit weird, "On start of layout" (Line 12) are link to "Active level 10" (Line 11) What is the reason for it to be link to that only, ain't all the levels the same in regards to the high score or?
But as already mentioned its not easy to debug that much code, but think you could try to make a level tester, in the sense that you make a button or a key, that when you press it advance the level by one, and then you check that the variables that have something to do with switching levels are correct. So run it in the debugger and each time you switch level you go through the relevant variables and check that they are correct.