1: My intent was not to imply that you should change the DTD for i18n translation files, it was more about the choice of an intermediary format that translators could use to ease their work.
2: I missed this recent github repository dedicated to translations
well done ...
3: About JSON/JS string repeating problems : My principal concern here is that, since many years, display of several reports simply fails when French is used to populate the repository. Root causes of these defects are mainly because of bad string handling in JS/JSON. Be these JS/JSON strings produced statically in reports or accessed through the API. Moreover it also remind me of some regression problems where reports were fixed in a revision but were defecting again in a new one.
IMHO, if EAS is to take seriously i18n into account, 1) work should not be on translation first but rather, an higher priority should be given to these string handling problems and 2) some automated tests should be used to check that problems of this kind are not occurring again and again.