I've had fairly good luck by manipulating those numbers in const.txt. But what I was attempting to get was a map of many large islands with consistent terrain (no more swamps surrounding deserts and/or snow). Plus I wanted some large mountain chains not just a few here and there. Plus I get almost no snow in the middle half of the map. The only prob I'm having is no matter what I do, the map is still mostly plains.
It took me along time to get the settings the way I wanted and I still occasionally get the random map that has no correlation to my wants.
Keep fiddling, you are on the right path. But also try various slide settings for each change too.
Good luck.