I was always told that the current 49PAK was included in the current Audiophile and I did not need to purchase it as it contains only wma files.
Reaper has a batch converter to convert all wav or wma files to FLAC, it should have an option to skip the folders with that already contain FLAC and remove source file after conversion.
You can also do a file search for *.wav with explorer then drag and drop them all into Reaper Batch converter and convert to FLAC removing source wav files after.

Working In Biab & Reaper Simultaneously and Instantly you can change the file type to FLAC in this Reaper script as Reaper will handle FLAC without decompressing:
Import-frozen-SGU-MGU-realtracks-drums-tracks-GUI.zip

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It will pull tracks or track sections from SGU or currently running Biab you are working on instantly with no rendering of wav files,
you simply have all the tracks frozen, Save Biab then hit the Reload Tracks button in the Reaper script:
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