I've just finished scanning my Kindle drive with Recuva and interestingly realized that they've deleted bunch of dictionaries and that space was later overwritten with a "GER DEFA.ult" file that had 1.8 GB file size.. and Recuva comment states that file data was overwritten by "/system" directory.
And ungodly amount of log files was removed at some point in time. One of txt files mentiones "/mnt/data/update-J140001-bellatrix_malbec-006.bin".