There may be an issue with the balance between javelin-armed infantry and javelin-armed skirmishers, IMO. It seems like infantry just absolutely destroy skirmishers once they are in range; 300 javelins being thrown at 175 dudes (probably with worse armor) seems like a pretty lopsided fight. and since they now basically function the same way it seems like you would be better off with javelin-throwing infantry over skirmishers 9 times out of 10. Maybe the ranges on skirmishers should move up a tier? Or the fire rate?
Speaking of, the soulferra throwers that Edetani gets are nuts. I wouldn't necessarily say overpowered, but they are fun as hell to use.