Hi Christian, has this matter progressed by any chance?
I work in Western Africa, we are constantly using both English and French. Most of our meetings are with countries of the region, and are often recorded, with transcripts, but most people just don't get it and don't figure out that they have to manually go to the transcript window to adjust the spoken language. As a result, many transcripts are gibberish. This is a great lost opportunity and value for us. We could in theory have a written record of the meetings, i.e. a searchable one, and also a readable one, as opposed to the videos, which personally I don't like (too slow and not searchable).
It's really a waste, a lost opportunity.
What would be best is to have every person's spoken languages registered so that the transcript would identify which one the person is speaking. For many people it would be just one, so, no mystery there, and for the rest, there would usually not be too much to chose from (usually 2, and even if the person speaks more, it's not often that they have meetings in all their languages). We have a lot of meetings at the regional level that involve both anglophones and francophones, so just setting the language once in the transcript window does not cut it. I have tried to change it as the conversation goes, it's not workable.
The fallback option would be to set the planned spoken language at the moment the meeting is being set up, but the first option would of course be much more useful (assuming you can actually detect the spoken language with some ease).
Looking forward for those improvements.