Wait, so are you saying that this problem is only when you do CUSTOM battles?
If so...who cares?? Custom battles are just a tiny drop of goodness compared to what the Main gameplay of this mod has to offer. What about regular single player gameplay? Are your Serbian troops still without equipment then?
Dude...seriously, you should play the game 1st and do a little homework before you post stuff like this. It's not like it's hard.
1) you start a new game as a noble for example...play for 10 mins and hire some Serbian troops.
2) get into a fight and then CONFIRM that they have their equipment.
Tada... you have your answer.