@dankcushions Thanks for your very elaborate answer! I naïvely assumed that at least the region detection was straightforward (e.g. some flag in the internal ROM header), but after some reading it seems that the region was indeed only "coded" physically by incompatible cartridge sizes. Some bytes of code and data saved I guess.

I'll just manually set the 50Hz rate. I'm definitely grateful that it can be done conveniently in a few seconds!