To be honest is quite a pain in the ass that in a medium/late game the only reason to produce any Manganese into Manganese Pellets is to get Powdered Tungsten, Plus the manganese doesn't have a pure ore recipe like the other ores, maybe if you could add a pure ore recipe using a catalyst....please? :D

Well I have had a look into this I think its fine as is and its not that hard to get manganese from ferrus sorting as early game if you want more options for sorting you can add Madclowns01 Processing mod he adds chrome/manganese sorting with cataylsts.

I checked the mod and it adds tbat combo from another of his mods, that would mean a new game

you don't need a new game for madclowns as far as I was aware new ores should gen in the unexplored area if you need them.