Revised the design around a TCA8418 keypad scanner: all 20 diodes were removed, the 5×4 matrix now connects only to the scanner, and I²C, INT, RESET, decoupling, and required pull-ups were added. The potentiometer and latching-switch sections remain intact; ERC and legibility checks are clean.
The project specification, firmware guide, and bring-up plan were also updated for the TCA8418 architecture. The next priority is reviewing the schematic before starting PCB placement.