[DCP-o-matic] burnt-in subtitles naming

Dom it's supposed to lowercase the language of burnt-in subtitles, but I can't figure out when does it. I tried a few times with subtitles already burnt in the source video and they are always upper cased. As I see it, if I add a subtitle language on the ISDCF name dialog and there is no subtitle track by dom, it could be considered as burnt-in in the source material. Upper casing only when dom is creating a track. Manuel AC