Number format for a locale language

How do I check the custom.properties file for internationalization as a system administrator?

Problem: I want to change the number format for one of the locale [el] which doesn't render in the floatingpointField as expected (12.345.99)

In support guides it does state for [dl] the dot is used for 1000 separator and comma for  decimal but not available for el.

Is there a way to make this work?

The common functions using substitute,fixed  and right to be called for a huge data entry function is not much helpful when we have a language support for Greek.