Currently there are two issues that prevents the dutch language pack (in develop branch) being loaded correctly.
Incorrect file name. The file name is currently bundle_nl.properties, but it should be Bundle_nl.properties in order to be loaded correctly.
The word "choice" should not be translated in some cases as choice is suppose to be a functionality within the dataverse (i assume). This will give an error in the home page if you try to use the language pack. Therefore, some translation "keuze" are changed back to choice.
Currently there are two issues that prevents the dutch language pack (in develop branch) being loaded correctly.