"Disk quota exceeded"
Does that mean your MacOs has only a limited amount of drives it can hook up into it's registry of it's system? I'm sorry, I'm a noob with MacOS. Anyway I found this troubleshooting post. Maybe it helps.
As for Jedit suddenly throwing in symbols... can you open the file in another coding program/text file like for example Notepad ++ to see if it still throws in symbols? (Notepad++ is free and opensource. No bloat or adware)
https://notepad-plus-plus.org/
If it doesn't then something is wrong with the settings of the Jedit program.
"You can try opening those files with windows' western charset cp1252 (aka windows-1252) because the euro sign € is not in latin-1 (aka iso-8859-1). In the open dialog you can choose your encoding in Commands/Encodings. Otherwise do you know Unicode?"
Otherwise I would post your problem to a programming community. Reddit allows you to make throwaway accounts without an email. So that is a quick and painless option.