Hi there, yes there is a bug in Wireguard firmware, which prevents success using Wireguard on WAN2, when WAN1 is primary.
We can fix that with some trickery.
A quick perusal of your config also shows that you have other issues that need to be addressed first.
a. you are port forwarding on ether1, HOW? If you cannot use ether1 because its a private IP for wireguard, equally you cannot use ether1 for port forwarding.
b. You have other issues with WANs ( I dont see a working WAN2 ) and see errors..
add interface=9 list=WAN
add interface*=A* list=WAN
Until we get to the truth about requirements not worth it to look at the config.
I see you have two wireguard remote connections, that seems fine, wireguard address is fine.
The access list you created is problematic, especially using it as a WAN input source for ether2??
Not sure what you are trying to do here…more mysteries that need to be unravelled prior to any config review.