Hey Michael, thank you for reporting the issue. Although this is already a very good description, I was wondering if I understood it correctly, that this "feature" has not been implemented yet.
( I agree that it would be logical that it works, just wondering if it was working previously...)
Then I would label it as a feature/bug depending on your answer :)

@NinaHerrmann, sorry it was my fault. I didn't mean editing but the functions under Manage Transcriptions that Farbod has implemented and that used to work in older versions of the plugin/Opencast version: upload, download, overwrite or delete of a vtt file.

According to Michael, the only thing that has problem right now is the download of subtitles under "Action" -> "Manage Transcriptions"

The outcome of our debugging session:

• (Opencast side) The subtitles generated by Amberscript or Whisper workflows, do not show up in the Transcription Management, the reason is the missing configuration parts in those workflows to provide the generated caption as media (assets) in opencast.
• (Opencast side) The Manually upload transcriptions via Transcription Management or parallel with video upload do not show up in the direct download list, the reason is again the missing configuration part in the republish-and-caption workflow in opencast to have it as publication.
• (Plugin side) If you manually upload the same transcription (with same flavor) via Transcription Management in order to overwrite, you will end up with a new one instead of a replacement, which has to be taken care of in the plugin!
  Hope the points were clear!