I think it should be possible and not too hard using the functions provided by the CountryFilter plugin. It would be a good idea indeed, people would get the auto translation directly in their language instead of the default English one.
Would it be an idea to extend this a bit more and let people decide whether they want the translation or not?
Using the CountryFilter plugin a !command like: !translate without argument would give them a translation in their own language, !translate Uk would give them the translation in English, !translate sw in swedish, ect. !translate off would turn it off.
Another question i have is: Would it be possible to give the autotranslate more than one source language?
On our server we play with alot of dutch people who all speak english very well. The plugin translates evrything, which sometimes gets annoying. But we also have a few people from Sweden, Finland and France who dont speak english. Would it be possible to make the autotranslator work with only those 3 languages translated to english?