CRX/SCL and CTX/SDA are STM32 pins connected to the BlackEdge connector which also connect through onto SCL/SDA on the Raspberry pi like header. This can be either I2C or CAN coms dependent on firmware.
Again these are connected through on the BlackEdge headers:
ESS connects to L3
ESCK connects to SCK
EMOSI connects to MOSI
EMISO connects to MISO
They can be used to connect a SPI slave device