I suggest you ask the question on the Templot Forum, plenty of help there, I can sort most Templot problems, but the 3d stuff is above my pay grade. John (Hayfield) may be able to help if he sees this thread.
Templot is an old program. I started the beginnings of it 46 years ago in the Autumn of 1979. A public version for Windows PCs was first released on floppy disk in 1998. There is a great deal of the original code still in there. It is simply my hobby, not a commercial product, so I don't see any reason to spend time changing stuff that works.
However, it is now open-source. So if you want to change it, you are welcome to do so.