The app fails when export-hashes CLI option is called and no export-hashes directory is present in binary directory. After spending few hours on processing pcaps this may be quite frustrating - app should create the directory or at least ask the user. Probably writing to OS default temp directory and then moving to per OS default location like current directory or $HOME/BruteShark/${date}/export-

You should order masks by efficiency (occurrences/key_space) because this will lead to the less guesses to crack passwords.

Looking at the top 5:
https://github.com/kaonashi-passwords/Kaonashi/blob/5239bd333ed34993b43126a4499606ba70086034/masks/kaonashi_masks_numbered.txt#L1-L5

And ordering just the 1000 in kaonashi_masks_numbered.txt by efficiency the top 5 are now:

673407:?u?u?u?u