passwords with non-ASCII chars will not work if OS is upgraded to 4.4.2/android-20/KitKat
Due to a bug in Android's implementation of
PBKDF2WithHmacSHA1, which is what CacheWord uses. It was only using the first 8-bits of any unicode character when deriving a key from a password. This was fixed in KitKat, but that means that a password with non-ASCII characters in it will then cause a different key to be generated since it is now using all the bits of the unicode characters.
So if a user installed this app on <4.4.2, set a password with non-ASCII characters, then upgraded to 4.4/KitKat or newer, they will be locked out.
This should be entirely handled in CacheWord, but that has not be done yet.