Terrae Expugnandae Issue

i am currently playing Terrae Expugnandae 5.1 mod. i am playing the armenian faction. during the battles i`ve noticed that when issuing orders to the mounted archers they do not really follow them and instead shoot at the targets of their choosing. the problem becomes especially worse when the units are grouped and i have to ungroup them and issue oreders individually for the units to do what i want them to. i have not played a vanila rtw in a while and i remember i had an issue with ordering move/attack orders to julii infantry where they would go off and do their thing when grouped. now, my question - is there a fix for this or this is one of those things where it is not a bug, it's a feature thing. while it may be a realistic portrayal of confusion on the battle field, it is still a highly annoying game feature.