geopark=yes would only mean it is a geopark, which can be national, transnational, or “regional”/continental as well. Need to start with at least eg geopark=global .
The problem is geoparks can be applied to any protection, =national_park , other =protected_area , or =nature_reserve , etc. Some complexity in interfacing.
The existing geopark= are freeform text for the naming. They will need to be moved to eg geopark:name= if the above is adopted.