I have the Kinesis Advantage2 keyboard and have used it for about 7 years now. I can't imagine ever switching to anything else. Why are you switching from something that works for you? Just like the Kinesis, any change to keyboard layout is going to take some time to get used to. It took about 3 weeks before I felt at home with the Kinesis.

For me it’s all about major tenting—like nearly 90 degrees—to keep my wrists in a neutral “handshake” position. Having my wrists rotated to be use a keyboard that’s facing straight up gives me carpal tunnel. You could try tenting your Sofle or Kyria to see if that helps.

right hand pain.

Any sense for what is different between your hands? You sure this isn't a mouse issue?

What kind of motions cause the pain?

There are 3 basic types of wrist motions rotating along each axis. Potentially you're either doing a lot of motion in one of these categories or your normal resting position isn't neutral in one of these categories. Maybe try to figure out which of these motions/positions is causing you issues and come up with ways to try to cut back on that motion or position the keyboard more neutrally in that axis.

Also, you should look into doing exercises to help with your issue.

Disclaimer: I haven't used a keywell keyboard.

Does the keywell cause the use of different muscles and finger joints to press keys? On a flat keyboard, key strokes seem to move the whole finger from the knuckle. If a keywell results in a curling or stretching motion of the fingers to actuate the keys, that would use different muscles and move different joints.

Another thing would be whether you're using wrist rests differently.