I agree I suspect its the latter point. I am not convinced a higher capacity rated EVSE will actually deliver anything more that the car asks for or try overcome any resistance losses encountered by excessive cable length or cold temperature. In fact the EVSE cable conductor resistance should decrease with cold temperatures. Yes there are cold temperature related losses related to AC to DC charging and heating a cold lithium battery but the EVSE/cable performance should be negligibly affected and perhaps even perform better in cold conditions. In the end we have to remind ourselves an EVSE is just fancy safety interface between your car and your home's electrical service. Its job isn't to push electrons to you car, its just a gate that allows electrons to flow safely to your onboard charger up to a max amperage limited by software and relays in the EVSE. All the charging magic otherwise happens in the car itself.