Only adding the fallback line should not work. With the fix for v6.23 I added the fallback feature since this can generally happen for other Github releases as well. To fix on v6.22 the following should work:
sed -i 's#"$(curl -s "$INSTALL_URL_ADDRESS" | grep -m1 "browser_download_url.*emby-server-deb_.*_$arch\\.deb" | cut -d \\" -f 4)"#"https://github.com/MediaBrowser/Emby.Releases/releases/download/4.0.2.0/emby-server-deb_4.0.2.0_$arch.deb"#' /DietPi/dietpi/dietpi-software
/DietPi/dietpi/software install 41 # to rerun the Emby install
Sorry, yes it was your fix posted in the other thread that acutally fixed this, I had done both but when trying again just by adding the line it did not work.