Investigate language clustering using an ontology such as Glottolog #377

From the feedback document "Unexpected behaviour of the VLO":

For some languages (such as German), a lot of different variants are available, including variants in different languages (“Mitteldeutsch”, “Oberdeutsch”, “German”, “German, Middle High (ca. 1050-1500)”, ...). They are not all standard German and not all tagged as German, so it isn’t easy to find them all. Typological hierarchies can be disputed, but the ~5438 different languages currently listed are difficult to navigate.

We would need to think how to present this and make it “facet ready”. One way could be to predefine a set of relevant language groups (perhaps determined by frequency??) and enhance the index with these.