v1 used compression attributes which confused sb3u. to fix files packed with v1, simply run v2 over the packed folder, and sb3u should be able to open the re-compressed files.
sb3u also serves as unpacker - if you save packed bundle in there, you should end up with the original uncompressed file.
Select folder, such as abdata, or some subfolder in it - you can try just with
abdata/chara to see what happens.
Re-compressing same data is harmless, as the program internally decompresses the bundle first, yielding same result if already packed. If a bundle can't be decompressed/compressed for some reason, it's left untouched.
Sound files are skipped implicitly.