Yeah, Hindi’s a bit of a mess, but we’re working on it. I don’t consider a language “supported” unless it’s got full subtitles for the whole trilogy. Hindi subtitles are just a few lines to cover the Greedo/Jabba dialogue, when you’re watching with the dub. And even then, some lines are translated by someone who knows the language and some are Google Translate by-products. I’m working on fixing that last part right now.
So, as for showing up as the default track, I’m updating my MKV instructions so that none of the subs are on by default (change the “default track” flag for all subtitle tracks from “determine automatically” to “no”). As for not showing up at all, you won’t see them unless you watch the Greedo scene or the Jabba scenes–there’s no subtitles to see in any other scenes.
If you live in an area with a big Hindi-speaking population, you can help! First off, the dubs–if any broadcaster shows the trilogy with the Hindi dub, record it (audio only is fine). I can use this to fill the gaps in the Hindi audio and make them complete. Even friends with old VHS tapes could help here. Secondly, the subtitles–I’ve got someone who I think is onboard only for translating a few alien dialogue lines, but can’t commit to translating the whole deal. However, translating everything is a much, much easier job when a dub exists (i.e. for the most part, you just need to transcribe the dub, not make a new translation), so you may be able to rope someone into doing this, using our English template files and the incomplete dubs.