Problem

Language filter has a very bad usability as list filter with hundreds of languages in it.

Solution

It should be changed to a text field filter.

The value in the field should do a text search in the language name and the language rfc-shortcut value. Language name respects the current UI language.

Multiple languages should be possible to search with comma separated search values.

To the tooltip on each of the language columns the following is added:

DE: (Filter für mehrere Sprachen durch Eingabe von durch Kommas getrennten Werten)

EN: (Filter for multiple languages by entering comma-seperated values)

This affects all columns marked red in the following screenshots: