I don’t know how the second encoder is addressed in the config. I read somewhere that it’s intended to be somehow autoconfigured.
From your schematics I think the first encoder at 0x20 is connected to the pins 36/37, but your wiring config states otherwise. It might be worth noting that when something’s stated as GPIO number, you might consider that being the WiringPi number. Right now your wiring config says the first MCP might be connected to pin 13 and 7, meaning WiringPi numbers 2 and 7, even it says “GPIO”
On your schematics the MCP at 0x21 the interrupts are connected to WiringPi No. 5 and 6, which would be physical pins 18 and 22, right?