First, on whatever keyboard you’re using, you can improve your posture and typing technique to make a big improvement:
1. Make sure your wrists and palms are “floating” above the keyboard, not resting on anything.
2. Try to get your chair/desk set up so that your back is straight, with your head looking straight ahead at the display, your elbows angled about 90°, and your wrists in as neutral position as you can get them. You may need a lower desk, a higher chair, an under-desk keyboard try, a higher display stand, or some combination of those.
3. Even on a standard keyboard, you want your hands coming in at an angle: you want to minimize any angle in your wrists.
4. Try to reduce the switches between mouse and keyboard if you can: moving a hand back and forth to the mouse repeatedly can be uncomfortable. If you use the mouse heavily, I think there are technique differences which can make an improvement, or switching to a trackball or trackpad might help.
5. Take breaks, switch positions, etc. Don’t sit in the same position for 5 hours at a time, but try to get up and stretch fairly frequently. Standing desks and various ergonomic chairs can help a lot with the discomfort of sitting.
6. Other exercise (like playing sports, or rock climbing, or swimming, or even just walking enough every day) can make a big difference.
7. For that matter, try not to spend too many hours typing on a computer, period. Go play outside, instead. :-)
But yeah, getting a keyboard with column stagger, some extra separation, tenting, and angle between the hands can make a big difference to wrist comfort.
If something is hurting, definitely take it seriously (it sounds like you’re on the right track, at least admitting there’s a problem), and don’t just try to tough it out: RSI is no joke, and dealing with it properly now is much better than piling on injury.