I was messing around in the startpos.esf file in the data/campaigns/main_rome folder and i got to change the size of the units which were actually existent in the campaign already, to double (COMPRESSED_DATA----CAMPAIGN)ENV----CAMPAIGN_MODEL----
WORLD----FACTION_ARRAY-0------FACTION_ARRAY-----ARMY_ARRAY-----ARMY_ARRAY-0------MILITARY_FORCE------UNIT_CONTAINER------UNITS_ARRAY-----UNITS_ARRAY-0-------UNIT). Lol, did only change the unit size already existent in on the map. New units just came out with 160 (hastati) instead of the 320 of the ones already on the map at the start.