You are wrong about 'spelt' though, on two counts. Firstly I don't use American spelling, secondly although 'spelt' is not the primary spelling in the USA it is used, as the graph below shows:
Shows the use of spelt and spelled in American books published in the 20th century.
This chart shows that the USA spelling is infesting the rest of the world, just like McDonald's is:
Shows the use of spelled and spelt in British English during the same period.