Actually, it was never intended that for be colored orange:
#FUNCTIONS COLOR #D35400 - ORANGE KEYWORD1
#FUNCTIONS COLOR #D35400 - ORANGE KEYWORD2
#STRUCTURE COLORS #728E00 - GREEN KEYWORD3
for KEYWORD3 For RESERVED_WORD
It's a subtle color difference, but if you look closely you will see that for does indeed have a different color from regular text.
I'm not aware of any flakeyness to keyword coloring in the Arduino IDE but certainly it's a crude system since there's no attempt to use context of the code so you get coloration for keywords from libraries that you aren't even using in the sketch.