We need to add some until now not existing languages to GRAV and the translations work fine but where can we add the long Language Name so that the two-letter abbreviation does not show up in the dropdown and instead the long name is showing up of a language?
@Andi, I think you will have to create a feature request at the repo of Grav.
The language codes with names and native names are hardcoded in /system/src/Grav/Common/Language/LanguageCodes.php.
Translations for a specific language are defined in /system/languages
You’ll have to create the translations for Admin and Core yourself though using Grav Admin translations in Crowdin and Grav Core translations in Crowdin.
See sample request.
uarg - that is not good - uff - why hard coded.
We need Swahili (Kiswahili) - sw and Myanmar (Burmese) - my and some others might follow too. The translation won’t work in crowdin as those languages are missing! So we had already to translate all those locally. But the only problem was persisting with the iso code and not the language longtext. I will see if I can create a pull request
@Andi, I’m not familiar with the ins-and-outs of Crowdin. You might consider contacting the Grav team.
Yep Thanks - I made pullrequests as we have people here which were working on the translations already but the problem with the language names wasn’t solved. - Let’s see.
I need to check out crowdin if that is at all suitable for bigger translations, and also if all plugins which we are using are actually available there too. Thanks for the help.
I just checked in Crowdin - for sure we won’t use that as it is way to complicated and harming a natural workflow of doing professional translations. There is no way to list all translations in a simple list and then go through it one by one, instead you always have to change even the view point on the screen and click click and click - much to complicated.
Right now our translations take place here locally and easily with our multinational team - no training necessary as all know how to work in a table 
and you have like in coding also the numbers of all rows just beside it so you can compare again and again with the original translation - much better and easier.
And much faster too!
I made a pull request!