But i think that javelin troops are quite okay already, all you have to do is to make the enemy focus on your infantry and use your velites to flank and shoot them from the rear. Also javelin are quite useful in siege especially high walls.

I agreed that javelin should carry more missile, but it won't be realistic i mean imagine a person running around with 10 javelin and lets say 1 javelins is 3 kg?, he will tire out very fast. Also i have seen that they put their javelin on tehir own buckler, bucklers are small so there is limit to how many you put on it, if too much the buckler will be useless because if they went to melle they can't use the buckler effectively since its gonna be very heavy.

The romans would prefer them to wear armour and become heavy infantry instead of going to battle and died tragically because of overweight buckler