Still in progress. This is for 3.3, which hasn't been released yet.
To import pre-made derivatives into Avalon via batch, use the original file name in the batch spreadsheet (example: movie.mp4) and set skip-transcoding to "yes". In the directory where avalon will look for movie.mp4, Avalon will look for the derivatives named with the quality added into the filename.
Example: movie.low.mp4, movie.medium.mp4, movie.high.mp4
You don't need to have all three derivatives to ingest. It can run with just one derivative of any quality.
If it doesn't find the derivatives, it will look for the original filename (movie.mp4).