I am not sure how much of a help it is, but people had been talking about Masuda Method in this thread, so I'll just dump the results of my experiments.
As people may or may not know, the stats inherited to the offspring are even determined before the egg is generated, thus you can save, generate the egg, take it, hatch it, check its IVs and look up which parent inherited what stat.
Now "international" and "normal" breeding use different algorithms when it comes to determining which stats are inherited, so there is always one inheritence spread for normal breeding and one for international breeding.
If you use a "Japanese" (meaning language set to Japanese but region still normal) and a Japanese (real Japanese one with both language and region set to Japan), the international inheritance spread is used instead of the normal one. If you use completely foreign parents, also the international inheritance spread is used. Which means that determining whether the international or normal inheritance algorithm is used is based on region settings.
It is most likely that the international breeding algorithm also makes shinies appear more frequently which means that international breeding and the Masuda Method are related to each other, but in the end people may whine because they only set the language to a foreign one for nothing and claim that this is just a theory (though everything points to it being the case) since we can't dig into the ROM and look that mechanics up.
Hope that information is helpful in any way.
(Also what I wonder is whether the chances of encountering a shiny had been increased. Instacheck uses that shiny values that are 12-bit long while the determination stays the same (XOR first 12 bits of LPID, UPID, SID and TID etc). If still the 13-bit numbers were used for determining shininess like in previous generations, there would have been a load of false positives within Instacheck and people would notice it early since very many people use it, but somehow I am not sure if I am just missing something that makes the chances remain 1:8192 instead of 1:4096.)