since there are enigma2 streaming tools out there, that support subtitles (Blackbox for iOS would be one example), i'm sure the subtitles come from OpenWebIF (or the default WebIF, for that matter) … i know they also come into VLC … now, whether one's able to embed them into a transcode directly via VLC, without the help of an outside solution, is ofc another story.

Much more important would be the change of audio channel tho.
As it is now, there are a handful of channels that are completely pointless for the end-user if changing the audio is not possible … this should be actually easy to implement, seeing as VLC can be told to use the respective audio stream when transcoding ?