At the end, I went for a polish CAA.
The process is much more straight forward and they are available for any help.
EASA says you can take the exam in any EASA country even thought you did the groundschool in another country.
Personal feeling is that they wouldn’t bother with me as I don’t speak Greek and because I am not student of a Greek ATO.
Obviously Greeks ATO won’t help you either unless you are register with them for the groundschool.
Would be nice to hear somebody who actually menage to go through it.