But is the 50 Hz power a problem? It sounds like it is not an issue. The Bolt most likely uses a rectifying inverter circuit to turn the AC power into DC power, so it should not matter if the supply is 50 Hz or 60 Hz. It would be nice to hear from Chevy directly on this question.
BTW: If you bring your own EVSE with you, this may be a non-problem. It looks like at least some of them (Aerovironment EVSEs) state that they can handle both frequencies, which means the car can too. The AC to DC inversion is done in the car, not in the charger. So all you may need is an adapter, and you can use any Level 2 charging station.
Speak up, Chevy: make the call on this subject.