The European database right lasts for only 15 years from each "substantial modification" of the database. The work in question dates from 1991 and contains mostly historical data so presumably those rights have expired.

No, it's not "definitely" anything in Europe, the database copyright issue is much more nuanced and has assorted exceptions, limitations, and requirements that normal copyrighted works do not, and courts tend to write small novels on the subject whenever an applicable case comes up.

(Not defending it, the concept of database copyright is mostly stupid, but you can't just say "databases are copyrightable", because that's not how the law actually works anywhere.)