Good question, and it makes me realize I should clarify my previous statement. There was a push in Japan to localize games for western markets by making them easier—you saw this with Super Mario Bros. 2; instead of releasing the actual SMB2 (later released as The Lost Levels), we got a re-skinned Doki Doki Panic, known in Japan as Super Mario Bros. USA. That's old news, of course. We also got easier versions of Final Fantasy II (released as FFIV), Phantasy Star II, Lufia, and many others. These tweaks usually came in the form of modified encounter rates, and boosted gold and experience points. I always thought that coddling was unnecessary, the type of people who would have bought Japanese RPGs in the '80s and '90s were likely the same type of people who mastered RPG mechanics from American PC games and D&D—the Venn Diagram is a circle. I mean, Gary Gygax lived on our side of the Atlantic.

On the other hand, some games were tweaked to be harder. Colloquially, this is because American publishers didn't want little Jimmy renting the game to conplete over a weekend, thus losing a potential sale. So, publishers had localization teams artificially ramp up the difficulty, as you see in Bayou Billy. The thought was, you'd have to own a game to put enough time into it to master, but the reality is, this didn't send us to Babbage's in droves to buy the hard thing, it usually just turned us off of the prospect completely. Don't get me wrong, a game that's hard from a result of good design is wonderful, but a game that's hard because Mr. Corpo Moneybags thinks a second '88 Testarossa would look good in his driveway is bunk.

Localization isn't a single line with a single metric, but my guess is (generally) Japanese localizers would make a game easier, while western localizers would make a game harder. There will always be exceptions to the rule, but my intuition tells me this is a very general case.