Ok the above shows that "Tetent " has been chorded in, where ^ is shift and | is the space location. I'd probably have to go back to vertical if a 4th Tetrinsic is used, but I've recently done a mental simulation and WOW only having to move 3 fingers most of the time is mentally liberating. I think I'll reject a 4th Tetrinsic on the premise of "mental overhead mitigation" instead of seeing if there's a technical, geometrical or ergonomical limitation.

Now, the reason why I've purposefully made the image above small is because the actual screens are small too, so this thing needs to be readable. I'm also trying to take advantage of the black pixels blending into the black bezel, and have moved the character zones towards the center.