Removal of translator rights
Your description of errors compare pretty well to the mistakes I see in new Finnish translation here. So far I've managed to review all new changes and correct them into good enough level for my taste. It has also made me to request documentation for many messages. We are also tying to reduce the barrier to make translations here by providing good and exhaustive message documentation.
But you are correct big enthusiasm is not enough, the translator must also be willing to learn. Also, if he has reverted translations back to his versions without discussing, that's very bad.
It's different - you know where to look it the code to find the message and to see it in context. We're doing it the hard way - with test local wikis, experimenting and trying to find the best possible translation that fits in the guidelines. Most of the users' contributions are not reviewed/edited (yet), I've followed them just to make sure they sound okay, but without comparing them with the original message. I just found several big differences from the source messages and will take care they appear correct asap, without being a raw machine translation or bad translation. In that case, instead of doing new translations, I have to review and compare old ones, have to imagine where they appear and which extension to load. As the most active Bulgarian contributor around, I still believe that it's better to have no translation, instead of bad one.
I only know MediaWiki and perhaps FreeCol. Most projects are unknown to me as well.
Nike, I perfectly well understand your strive to good faith. But... it's. not. a. matter. of. good. faith. here. This user, this very user, is a notorious example why the translator rights have to be given __in return__ of provided references for linguistic competence and experience with the IT/software terminology and MediaWiki. Otherwise, the lateral damage on the product itself, on its Wikimedian and external users, as well as the rest contributors who are forced to do double work, are greater. I can't explain it in a clearer way.