By capping to 25km/h they can likely stay within the regulations for small mopeds (not even requiring a proper driver licence and having relaxed requirements for the vehicle). If they go to 45km/h they would be treated as a regular scooter that requires a regular drivers licence (or a smaller one for slow vehicles). If they go 100km/h they would be treated as a motorcycle, requiring a special driver licence for motorcycles, and having to comply to safety requirements for motorcycles etc.
I don't think we will see them going over 45 km/h in Europe
As far as i understand Gogoro need to roll out their battery swap network/infra before they will sell the actual scooters as this is what their business model revolves around.