Thomas, the problem as I see it is that it may not just be the physical ac charger itself but loads of other factors plus ancillaries adjustments such as battery control module mapping, battery cooling, battery maintenance etc. If it was that easy why didn't Mazda just not give us a higher rated ac charger in the first place? Probably because charging at a higher rate than 6.6kwh, as the normal daily method, would/could damage or shorten the battery life hence the recommendations to use CCS charging more sparingly. Only my thoughts but there must be some Mazda/Panasonic reasoning behind it. Perhaps future versions may go higher but who knows?
Alan