I found a MAJOR bug in Hidden Grotto's generator. I tried modifying female Marill's percentage chance of appearing in Flocessy's ranch HG using your program and setting them to 100% (64 in hex) but for some reason I still got males. I used Drayano's excellent tutorial and found out that your program does only half of the job.
Please refer to the image to see where's problem: This time I tried setting Dunsparce's percentage in a very specific, easy to spot pattern of 100-30-100-30 (64 1E 64 1E).
Once I opened the .narc in CrystalTile, I saw not one, but TWO chunks of code specifying HG pokemon and items. One of them, beginning with CE 00... (code for dunsparce) had mine pattern of 64-1E-64-1E.
But below it there was another one, similar to it, except this time the pattern was "1E 1E 1E 1E", as if nothing has changed!
I assume from Drayano's tutorial that one part corresponds with White2 and another one with Black2. Since I play the latter, it seems your program modifies values for only one game.