This is wonderful AlanG, thank you very much! 
I have two suggestions for improvement or enhancement, but unfortunately my JS skills are not sufficient to do this myself:
- Do you know how to add property-keys to already existing ones and not overwriting them?
- The disadvantage of using templater templates is, that updating properties in the property pane won’t update templater templates. A workaround of this disadvantage could be, to include normal templates (which will be updated) through templater scripts. … I think there is the function tp.file.include(), which is probably meant for that, but I didn’t manage to get this working…
Thanks a lot in advance!