Correctomundo! Last one is the feature im looking for. I have the subs in the correct order in the container - but PVD likes to just mix that randomly
The fact they stay in the order they're put in is probably by design. That allows them to be put in priority order, and then that won't be changed back (I guess—I don't have any MKV's with multiple subs) if the file is rescanned. I suppose it would be simple enough to have them sorted according to a specified priority list, the that seems to be a trivial thing that's not going to affect many users. It has no impact on the playing of the files, as it's the player that is configured as to which subtitles to use. And as I mentioned, there are other things you can do if it's that important to you.
I only want the feature, for when exporting
When looking through the list of movies, its nice to see if it got the subs i want.
Its not something thats super important - not at all.