Language Overrides seems to work well

I just replace two language strings for CBSubs in the CB Default language (English) plugin. It seems to work like a charm. Also in the backend. This is a huge step forward.

Why do those language tags have this combination of numbers and letters in the end like CREDIT_NOTE_f33866?

We generate an MD5 for the language keys to keep the keys unique to their string. When overriding an existing string the key needs to be the exact string it self (its English string) or the key as seen in the language files, but custom language strings you can use whatever key you want.