Last week, I spent a few days working on the design for the PCB I'm going to replace the typewriter's keyboard with. I livestreamed the whole design process on YouTube, and after all that, I now have a pretty solid design! The KiCAD project files are available on GitHub. I've ordered the PCBs, and they should be arriving about a week from now! 

Schematic:

All Layers:

Front copper:

Back Copper: