Are these interchangeable?

Try to get the same nuts as was on those studs originally. They have a wide base and serrated teeth on the underside. When you torque them, the teeth bite into the levers and spread the clamp load, to better hang onto them. If you cannot get them, use the originals with lock-tite,and maybe ease off the torque spec.. Once the locking agent fills the gaps, the nut just has to keep the lever on the stud. A bit of thread-locker on the stud and in the nut, and it will be fine,so long as there is some threads to work with.
If you try any other type of self locking nut or a spring washer, they will all fail.
Through the shift stick, you are able to generate a tremendous amount of force on those levers,and if they move around on the studs,the nuts will work loose. I mean figure it out; the stick has a ratio of around 6 or 7 to one.And you can easily push with a force of say 80pounds;180 with a bit of shoulder. So average it out,say 130. That times 7 say is nearly 1000 pounds of force, going into the end of the lever.And you are not yet up to the stud.
Any other type of nut,without a locking agent in the gaps, will fail. When this happens on cruise night, with you dressed in your best, there is just no good excuse,lol.