RE: Futaba module retuning
It's really USA, not "North America". The FCC (Federal Communications Commission) controls frequencies and issues regulations regarding operation of radio equipment. These regulations carrytheforce of law. One interpretation of the regulations says it is illegal to change crystals in transmitters without having the transmitter retuned. Another interpretation says that is nonsesnse and anyone can change a crystal any time. The AMA, which provides liability insurance, follows the interpretation that it's illegal. I'm not a lawyer so I have no idea whether it is illegal or not; but I fly at an AMA club, so I'll follow their interpretation of the rules.
Since you're not in the US, you're not subject to FCC regulations.