Why the custom computer keyboard? Why not practice on a real soroban? They cost about US$10. You need to practice the finger motions, after all. They're not bad for addition and subtraction. For adding up small numbers, such as at a store checkout, a soroban is still useful. Multiplication, division, don't go there.

With a soroban and a slide rule, you can do most basic engineering problems.

I wanted to track my progress to the highest level of detail possible. The motor motions are somewhat similar, but slightly more complex, than typing on the keyboard. But since I already type fluently I wouldn't be able to get as fresh data, so the soroban was a nice other task.

The main goals were to track learning progress and truly experience what it meant to have a virtual abacus in my mind's eye.

Honored to get a comment from you!