There are a few missing things that wuld simplify things in managing translated templates. See Help talk:Extension:Translate/Page translation administration for details.
Note that the "TNT" template has been updated on Meta-Wiki, and is still being worked on to implement the Mediawiki standard fallbacks, still missing for now.
The Lua module also fixes various quirks (the version copied from Meta-Wiki to Commons doesn't have these features (notably it is still producing "Script errors" if the specified template name is still not marked in translation to generate the /en subpage: so as long as the source template is not marked you need to create manually the final "/en" version, used as the last default).