Hi Efthimios,
Especially with an aging application that attempts to handle internationalization for both content and UI elements, there are bound to be more issues that crop up ;)
In this case, there are two workarounds, one immediate, one more long-term:
First, the More menu will show up in the Translation menu, so you can immediately make a local translation. Here's an example of me finding the entry while in the French UI on the demo site:
This is short-term, because right now AtoM does not have a way to carry local UI translations forward into future upgrades. We have an old issue ticket for this here:
Meaning that for now, you will need to redo this and other similar interventions after upgrades.
The longer-term solution for new installations is to ensure that a translation has been added in Weblate, so it is part of the fixtures. I believe this has actually been done for Greek already:
...which brings us to the NEXT known issue - right now, newly translated fixtures (i.e. default database content like some terms, etc) are ONLY available in new installations - we do not have a method of making new fixture translations available following upgrades. I believe this is because the fixtures are stored in the code, and used to seed the database when it is first created... but when you upgrade, you overwrite the default new state by loading your previous database. Once again, we have an older wishlist ticket for this issue:
There are also other related i18n issue such as:
In the short term, I hope that using the local translation interface will help you get one step closer!