Overview of the Feature Request
A new API call for querying the metadata language of a Dataverse collection like this:
GET /dataverses/{alias}/metadataLanguage
If there are no metadata languages configured on the server, the response is an empty array.
If there are metadata languages configured on the server, but the collection doesn't have a mandatory metadata language, then the response is the array of available metadata languages as introduced here, otherwise the response is the mandatory metadata language.

What kind of user is the feature intended for?
(Example users roles: API User, Curator, Depositor, Guest, Superuser, Sysadmin)
API User

What inspired the request?
I found a bug in the RSpace Dataverse integration (reported here). This new API call would help fixing this issue.

Any open or closed issues related to this feature request?
Only in Rspace:
rspace-os/rspace-web#478
rspace-os/rspace-dataverse-adapter#2

Are you thinking about creating a pull request for this feature?
Help is always welcome, is this feature something you or your organization plan to implement?
Yes, I will open a pull request soon.