The original board works exactly as desired. This is not surprising as the circuit has been well tested by the many cheap displays using the same chip but have smaller digits. Even the higher forward voltage of 2 diode junctions per segment was taken care of by the TM1637 chip.

However I made a mistake, I put buttons on the PCB. I thought it would be an advantage, being able to use the TM1637 not just as an output device, but also as an input device. But the size limited the places I could use the board. I was too eager to use as much of the 100x100 limit for cheap boards as I could.

So I redid the board to hold the display only and no larger. I was not ready to lose the input capability, so I brought a subset of the input lines to a connector. With 4 segment lines and 2 keyboard lines, 8 buttons can be deployed, which should suffice for most purposes.

The design files are in a new Github repository. As with the first design it is a swap in replacement for the cheaper smaller displays, even the order of the power and signal lines in the connector is the same.