Either way, its not like there is a choice at this point.
Is this an answer to my original question? Is JRiver transitioning permanently from TVDB to TMDB?
Why would there need to be any conversion, manual or otherwise? They fill practically the same fields, even the TVDB ID is still being filled (and used, if the TMDB ID isn't present).
You're correct that the field names are similar between the two, but the data in those fields can vary significantly.
I suspect most popular serialized shows will have very similar, if not identical metadata, e.g., "Game of Thrones", "Stranger Things", etc.
Less popular and documentary shows are often subject to discussion and can vary significantly in episode order, and other metadata.
Example:
I was looking up metadata for the series "NOVA" using MC and TMDB today and the episode titled "Bigger Than T. Rex" is numbered S41E20 on TVDB and the series title is "NOVA"
Looking up the same episode on TMDB, I first have to tell MC the series name is "NOVA (1974)" so MC can find the proper episode number, then it matches it to S41E20 on TMDB which is titled "Why Sharks Attack". "Bigger Than T. Rex" is S42E07 on TMDB
This could possibly be addressed by adding some logic to check episode titles when looking up metadata, but it would require users to verify each match or trust an algorithm that could go horribly wrong.
Again, I'm curious to know if this switch is permanent or temporary?