I oppose this idea. IMHO the last thing we need is to open the floodgates to questions posted by high school students world wide, and this suggestion might make that easier. (IMVHO it would be better to shut the door to all high school level material - possibly with the exception of contest math - as they usually don't inspire answers of permanent value either. I am aware that there is no agreement like that, so I will not use my moderator powers to enforce this point of view.)
The questions asked in a Sami language (for example) may eventually start getting answered in Sami as well. Then sooner rather than later Sami speakers will have created their own private subforum inaccessible to most of the users.
And all proposals for versions of Math.SE in languages other than English have been shot down: e.g. Portuguese or Chinese. If you want to use language other than English it is better to have a separate site. Such proposals exist, but, as just stated, have not won enough support in the past.
I'm not opposed to translation requests and/or an occasional question in another language. Originally they were used/intended for translating passages of scientific texts. The cited thread, AFAICT, was about questions at or near research level.
If we try this inspite of me, I would like at least that
- the answers should be in English only,
- answers should not be posted until a translation has been provided.
Otherwise we will create separate markets for Q&As in any language. But managing/enforcing of such rules is a nightmare, so I vote to nip this in the bud.
Another problem with getting several questions in another language is that the community then loses the ability for immediate quality control.