Looks like fun. Investigating.
The copy <translation> in source document bug should be addressed in
done and merged, just waiting on a release schedule. I unfortunately couldn't put this into the recent 3.9, simply due to a high number of upgrades and workarounds surrounding Okapi and Jericho html parser (among others).
Related issues are the debatable above and for context in editor.
Thank you very much! I will try it after we upgraded Zanata here.