Honestly - I don't know and more honestly, I don't care also as I made two templates - one for EleksEGG and another for bigger flat ones. And as I don't like InkScape at all, the templates satisfied me, because anyway I make all my vector works in other programs, so InkScape is just G-code exporting tool for me and templates makes they work.
Studied little bit EleksMaker tool Python source code after reading @Zapf's solution that probably works, but I found one more place in code that must probably to be changed to work so that script can act as it must. But as I told - probably. I have not tested Zapf's nor mine solution about code change as it is more difficult to achieve for usual computer users then loading a template...
I use InkScape 0.92.1
Oh boy - was I wrong about thinking that saving and using template is easier then editing code. As we can see - even a simple file using can be over a mind for someone...