We are unable to guarantee that credits won't be lost by the plugin due to various issues such as the server not being able to reach the database or the map spontaneously restarting due to running out of memory. You can't just resend the command if it fails because you don't know if it actually succeeded but just failed to reply. People could then generate credits by ddosing the server.
It's possible to make it more robust but given the low number of players that use this feature, it isn't worth the time I'd have to spend. It is just a giant hassle to dig out logs to see if someone lost credits and sometimes impossible to tell.