Since you can choose the language of X & Y just before you start the game, does a different language Pokemon (for Masuda method) count from the language you set your game at, or from the region your 3DS is from?
Masuda Method is determined in Gen 6 onwards from the language chosen at the start of the game, not what region the cartridge came from.
The Pokemon must be in a language other than your current system language in order for it to count. This means that Trading UK<-->US or other English-speaking countries won't work.
Source
I made a whole answer as to why the Masuda Method relies on region-locked Pokemon.
Here it is! :D
Hope I help. :)