Thank you, what a neat solution, I didn't know that ep128emu was scriptable with LUA.
And thanks to this I found out I had some seriously off LPTs, running 304 lines at several places!
Seems like both ep128emu and my real Enterprise128+CRT TV didn't mind 304 lines though, it seemed to work fine.
But now of course I have adjusted so that it is proper 312 lines everywhere.