Hello Patryk
Keep in mind that an AVG and an AVF are two different things. The priority value configured will determine which switch will become AVG, but the weighting values will determine if a particular switch will be an AVF. Remember there is only one AVG, while all functioning switches in the group are AVFs.
Now in your scenario above, SW2 will be AVG. Even if both links to the router fail, it will still remain AVG. This is because even if both links fail, SW2 and SW1 still maintain a connection between them via the 192.168.1.0/24 subnet, so there is no reason why SW2 cannot continue to function as AVG. Remember, the AVG is responsible for answering Address Resolution Protocol (ARP) requests for the virtual IP address. Load sharing is achieved by the AVG replying to the ARP requests with different virtual MAC addresses. SW2 can continue to do this even if both its links fail.
If the currently active AVG fails in this function, only then will the backup AVG take over.
I hope this has been helpful!
Laz