I suspect that news of this group has never passed on this mailing list:
Open Knowledge Foundation's Working Group on Open Data in Linguistics
https://linguistics.okfn.org/
Open data is relevant for Wikimedia, Wikidata and Wiktionary in general,
but "Build and maintain an index of open linguistic data sources and
tools that link existing resources" seems useful for MediaWiki i18n too.
We have some moderate experience with sharing datasets related to
Apertium, content translation and so on, so perhaps we should keep an
eye on "Assemble best-practice guidelines and use cases concerning
creating, using and distributing data".
Federico