If qBittorrent/qb-nox is bound to your VPN interface, then 1) your VPN needs to support port forwarding, and 2) forwarding a port on your router is pointless and unnecessary. Your only way around it is to switch VPN or don't use VPN and then port forward.
If they're supposed to be binary-identical data (same file checksums), you can use BiglyBTs Swarm Merging feature - without manually copying (which isn't as reliable due to the start/end of the files not bordering on the chunk boundaries.
If they've been modified in any way though, this won't work. However, you might be able to use its Swarm Discovery to find other torrents with the same data and complete with Swarm Merging.
If qBittorrent/qb-nox is bound to your VPN interface, then 1) your VPN needs to support port forwarding, and 2) forwarding a port on your router is pointless and unnecessary. Your only way around it is to switch VPN or don't use VPN and then port forward.