SirKillian
I added the following tags to the entire railbike railroad:
usage=tourism
railway=preserved
operator=Spoorfietsen
website=https://www.spoorfietsen.be/

According to https://wiki.openstreetmap.org/wiki/Tag:railway=preserved
"Historical railway. Usually a tourist attraction."

I'll mark this note as resolved considering its been open for 3 years and it's current tagged the best way possible.