i dont think that is a viable option, the pop reduction from 2 to 1 results in a 100% increase in damage per pop since you can build 2 now for 1 before.
If you want to balance by reducing stats, their stats would have to be reduced by by about 40-50% which means the desert archer is actually worse then alot of existing units out of the gate and make massing them very difficult since they will just get sniped off
edit: it would also make the outlaws completely unviable for hausa since they dont even get the pop reduction and just a 10% combat card, so the current stats of the units are very important for them