'semi-governmental company'
If they're using it in prod then there are plenty of regulations that should force them to establish a real support relationship.
Sometimes this type of stuff happens for a prototype that an org is trying to get funded, but not for 10 years. I'd collect all of the org email addresses they used for the initial d/ls and contact them first- maybe one of the ones from ten years ago has gotten promoted to a point where they can establish a paid relationship or approve use of the open source version.