I just watched trailers in English, German, French & Spanish. 1 important thing to note is the language is set at the point of the scan, not at playback.
There's also a file stored in PreShow's data so that you can hammer the scraper, so the trailer language can't be updated quickly unless that file is deleted. In other words, you can't quickly change between languages.
I went with what I think would be the 10 most common NA or European languages. This should be in the next dev or official version of PreShow.
Also, I'm going to change the title of this topic since it affects other languages.