Forest Hills is primarily for Needham Line trains. The Providence/Stoughton trains don't typically stop, although I think there is one a day, but that may not have been the case for the represented time period. I am guessing this is the reason why Forest Hills was not fully represented; of course, if it was made into a fully available station, then perhaps Needham trains could become driveable services, but that would be the last represented stop for them.