The new input interface for the "Subject" and "Language" fields is awesome. Why not generalize it?
Version: 4.20
Guten Tag,
We really like the new input interface for those fields:

Perhaps it could be generalized to all other fields that consist in a drop-drown menu with fixed values? E.g. "Geographic Coverage" > "Country / Nation."
One of our project partners told us she was surprised when, having selected the drop-down menu for that same field, she started typing b e l in order to get "Belgium," but instead of receiving the letters as a unified sequence the software took them one at a time and eventually led her to "Lao People's Democratic Republic." This problem would be fixed with the new input interface.
@BPeuch good idea. I just wanted to point out that this interface isn't limited to those two fields. It's applied programatically based on features of the metadata field. It also applies to "Type" in the astro block, for example:
As you say, it's doesn't apply to "Country/Nation". Here's a screenshot.
~~TODO: put the pull request here where subject, language, etc. were changed to use the new interface.~~ See also pull request #6339 (subjects disappear on edit) where the new interface was introduced.