According to new Bose Updater I prepared third option how to downgrade. Just run reverse proxy on your PC and mock /connected_device endpoint, then you do not have to hex-edit BU software ;).

Here is an example how I did it:

1. install nginx (I used Windows WSL Ubuntu)
2. generate self-signed certificate
3. set new nginx config (see below)
4. mock worldwide.bose.com to 127.0.0.1 in hosts file
5. go to https://worldwide.bose.com, it should have certificate error
6. import that certificate as trusted
7. run Bose Update - it should be without any error in log file
8. same as before

nginx config

server {
    listen 443 default ssl;
    ssl_certificate /etc/ssl/certs/nginx-selfsigned.crt;
    ssl_certificate_key /etc/ssl/private/nginx-selfsigned.key;

    location = /connected_device {
        proxy_buffering off;
        proxy_pass https://raw.githubusercontent.com/bosefirmware/ced/master/lookup.xml;
    }

    location / {
        proxy_ssl_server_name on;
        proxy_buffering off;
        proxy_pass https://worldwide.bose.com/;
    }
}

generating self-signed cert ...
sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/ssl/private/nginx-selfsigned.key -out /etc/ssl/certs/nginx-selfsigned.crt
set all defaults except Common name - *.bose.com

hosts file in C:\Windows\System32\drivers\etc\hosts
127.0.0.1 worldwide.bose.com

It might be even more elegant, but it works anyway ;) enjoy
Lipo