I have uploaded V0.2 of the schematic. Here is everything that has changed from V0.1.

• Added ESD diodes on USB C CC nets.
• Added single use fuse on VBUS. I wanted to use a re-settable fuse, but finding one that works up to 20V 5A that is small and cheap is tough. So I went with a one time fuse.
• Added balancing circuity.
• Switched to a slightly larger version of the STM32 to support all the IO needed. I initially underestimated the amount of GPIO's needed for the project.
• Added voltage divider networks for the ADC inputs to the STM32 for reading individual cell voltages.
• Added RGB LED for debugging and user feedback.
• Added UART from the STM32 for debugging. I may still add a UART to USB bridge for programming through the USB C port.
• Added 3.3V linear regulator. Needed to support up to 20V from Vbus and be a low drop out when VBUS is 5V.
• Added circuit to automatically steer the output of the adjustable regulator depending on what type of battery is connected (1s-4s).

I still need to add the supporting components around the adjustable regulator.