After using the English v4 symbols layout I'm wondering if the numberpad is even needed. One of my problems with thumbkey is that you have to switch to the numpad for numbers where on normal keyboards you could just have the numbers above the keyboard.
There's enough open spots (specifically s and o) where swipes for numbers could be added so you don't have to keep switching between the letter and number layouts.
@Zenaida_macroura I like to have the numberpad separate so that there are fewer symbols on the main keyboard - that means I don't need to swipe quite as accurately to hit the right symbol.