The actual bottleneck in the project seems that a missing c++ expert for: “Add hstore support to Mapnik’s c++ code – this will allow all languages to be stored in the vector tiles simultaneously.”[1]

Perhaps you know someone.

Greetings Tim

[1]https://lists.wikimedia.org/pipermail/maps-l/2015-September/001439.html

Hello PlaneMad, original project page is here: http://wiki.openstreetmap.org/wiki/Multilingual_maps_Wikipedia_project

I18n of maps is still a topic at Wikimedia: https://phabricator.wikimedia.org/T112948 Should come to production with help of Mapbox’s vector tiles rendering. Perhaps you have a chance to support the project.