Sharing my experience after trying everything available.
1- Smart word list attack from android-keystore-password-recover is what eventually worked for me after spending a day trying different lists. Unfortunately, it does not support multithreading and I couldn’t get it to run faster than 30,000 trials/second. I might contribute multithreading support to project soon.
2- KeystoreBrute was the best for brute-force attack at 320,000 trials/second. However, if you do the numbers, it will take 3.5 days for 6 characters long password and 177 days for 7 characters long.
3- If you only need to crack the keystore password, but not the certificate password (also referred to as the alias password), this tool will just changes it for you.
Good luck!