the steps I followed in detail are:
I created an account in Transifex and I created the '.transifexrc' file with the details requested (including username / password).
In the 'apps/edx/edx-platform/i18n-tools/i18n/transifexrc.py' file, I replaced the: 'tx pull --mode=reviewed -l ' + lang command with: 'tx pull -l' + lang command.
I executed 'tx pull -l el' and I got the latest greek translations from Transifex.
I executed 'apps/edx/edx-platform/i18n-tools/i18n$ python generate.py' to generate the django.po, djangojs.po and all .mo files.
I inserted the following to these files:
apps/edx/conf/lms.env.json' -> "LANGUAGE_CODE": "el",
apps/edx/conf/cms.env.json' -> "LANGUAGE_CODE": "el",
apps/edx/edx-platform/lms/envs/common.py' -> "LANGUAGE_CODE = 'el',
apps/edx/edx-platform/cms/envs/common.py' -> "LANGUAGE_CODE = 'el'
I restarted the servers.
And this procedure is working quite well for most of the translations.
The problem is for translations that are in specific views, like forum, profile, account, search that the greek translations (that exist in the .po files) do not show up.
In my internet search I found that these commands:
'cd apps/edx/edx-platform/' and
'sudo bin/python.edxapp ./manage.py lms compilejsi18n --settings=aws'
regenerate the 'apps/edx/edx-platform/lms/static/js/i18n/el/djangojs.js' file and insert the translations in unicode format.
But no success also with this one.