Yes, I'd say the sprayers are just barely adequate. I would doubt there's any adjustability in them. At highway speeds, the spray is hitting the glass below the wipers so not as much gets up higher on the glass until you've kept the spray on for a bit.
I have a feeling it's just the design of the vehicle and there won't be any way to improve it.
It would be interesting to know if someone figures out a way to improve it.
I haven't looked at them yet, but most of them are adjustable. You may be able to adjust them by taking a pin, sticking it in the hole (gently) and shifting the little plastic ball inside so the hole points where you want it.
Every car I've had so far, works this way. Every car has had the problem of different speeds causing the spray to land in different places. You have to play with it to find the right spot.
I have problems with both the wipers and the fluid. They do the job, but not as well as the average car. Probably due to the oversized windshield. You really have to pour the fluid on to get any results. They could improve the wipers by adding more pressure/spring to them so that they clean better and faster.