I say, you move beyond the edit and evaluate the worth of the post. If the original post (subjected to translation, when required) holds value to the question (more than just a comment, but may not be a full-fledged answer) and the edit doesn't change the intent of the post, than accept or improve the edit.
If the post isn't worth to be an answer at first place or cannot be salvaged or should be a comment, than there is no point in accepting that edit. It would only bring that unworthy post on the front page under Active tab for no good reason. Furthermore, it would award the editor with +2 score. The reputation doesn't matter much here but the encouragement of having such an edit accepted may harm the site in future.
Harmful! How come?
Reviewers are supposed to keep a tab on the quality of the posts on the Stack Exchange sites. Whatever they do, it becomes the norm soon.
- If they begin to accept LQP as worthy to be retained, quality of the site decreases since more LQP is equivalent to more unsatisfied and frustrated users and viewers.
- If they accept low quality edits, they begin to raise an editor with poor editing skill and judgement, and that user, after 2k score, would raise alike editors through their poor reviewing and unrestricted editing.
- If they upvote an LQP, others might take that such posts are actually of worth on this site. And users taking LQP as acceptable is never good for any site.
What to do than, other than to reject the edit?
- Just copy-paste the translation, to the extant it is permitted, as a comment on that post so that other users do not indulge in the same editing process.
- Use your judgement towards that LQP accordingly so that other new editors and viewers don't get to see it anymore.
- Ping that editor in a chat and let them know, kindly of course, why such edits should be avoided. It could be a canned response. Alternatively, you could avoid this by having the reason cited when you reject that edit.
Alright, enough opinion for now.