I’m running out the door, so sorry for keeping this a little terse. Just wanted to throw out some things for you to potentially look into with regards to your USB-C port in case you were about to send this PCB off for fabbing.

1 - Consider including an ESD Protection chip. It’s a small IC which you pass your data lines through. It can help protect your microcontroller in case there’s some static electricity in the cable you’re plugging in.

2 - There’s a variety of different detection mechanisms and handshakes in USB-C to identify the amount of power a USB-C device supports. Adding a pair of 5.1K resistors to the CC1 and CC2 pins on your USB-C port will definitively tell the device on the other end that your keyboard is a simple USB 2 device and should get a nice chill 5V. Some devices will default to providing 5V is CC1 and CC2 are left floating, but others are more picky. Adding the two 5.1K resistors will help make sure you don’t run into any trouble with a USB-C to USB-C cable.

3 - I’m less confident on the specifics of this one, so maybe do a bit of research yourself. Most of the USB-C implementations I’ve seen on keyboards tie the redundant pins on the USB-C port together. I believe some of these are only connected when the cable’s face up, and others are only connected when the cable’s face down. Routing them together on your board will make sure you don’t run into any trouble with cheap USB-C to USB-A cables.

Here’s a quick example of those three items in action. (Ignore the weird vias and disconnected ground nets. I deleted the fill to make it easier to read.)

Sorry to post and run. Hope that helps!

Another recommendation to take a look at the Sofle. It’s got a lot of the positives from the Corne, but it also has a number row and plenty of mod keys to help ease the transition.

I like the look of it! I wouldn’t worry about the arrow cluster too much. If you want it, you want it. There’s some keyboards out there like the Afternoon Breeze or the RevXL that put it off to the right. It makes the board asymmetrical, but it would play a bit more into some of your existing muscle memory.