@dennis First off, thanks for thinking about the Twiddler3 as a solution to your input issues. My first recommendation is to create a Tuner account. It's free and you can start to develop an understanding on just what you can do with the Twiddler3.
My second recommendation is to think about the Twiddler3 as an HID packet sender. It just sends HID packets to the OS which, in turn, changes them, to letters you see onscreen. While a single keypress on a keyboard usually only sends one HID code, a single chord on the Twiddler3 can send up to 2MB of HID codes. So, construct your entire key string in a single chord with modifiers (Ctrl-Alt-Shift) and then you do not have to press the C-A-S keys with your thumb.
Finally, while you have to press every key in the chord in order to "make" the chord, it is the release of a single key that sends that chord to the OS. I use Tab a lot. It's chord is MM0M. If i need to have 3 tabs in a row, I just chord MM0M and then raise and press the last M with my pinky finger 2 more times. It's fast and doesn't require a lot of finger movement.