In my previous we had dozens of source files and tons of translated strings (both in project and translation memory).
We had a need to reorganize our source files due to our product change - to group strings together more logically and make it easier for translators, maybe add some context in the context field or screenshots.
We’ve just deleted everything, uploaded new sources and pre-translate with translation memory. All authority of translations were lost, same as reports (weekly/monthly progress). Those days we didn’t care about it, by time has changed.
Now I’m curios about the best practices on the matter. We’ll have same product update this summer, need to plan localization strategy right now, I guess.