https://www.mediawiki.org/w/index.php?title=API&diff=5680004&oldid=5679881
What's wrong about that markup? I thought that's the right markup if you want to enable translations.
Topic on User talk:Shirayuki
You must imagine it as a translator. The TU as you created was totally wrong. The main task of markup is simple TU without wiki markup for minimize potentially problems.
I recommend read manual before for markup examples – Help:Extension:Translate/Page_translation_administration