I just happened to be reading this older string. For anyone who finds it, editing the templates is really quite easy. Make a note from the existing template. Edit it. Choose ‘Save as Template”.
To see your new version, open a new note. Click the use template button. While you’re in there, delete the old version if you’re replacing the old one, and not making a ‘Version B’.
As templates concept is to host notes that are likely to be rarely edited, this process seems fine to me. Makes it difficult to accidentally edit your master copy of the template.