Your description is correct for the configuration files, yes! But it's not correct for the app. There are multiple ways of doing multihop with Mullvad. The config files use a simple redirect where each server has a unique port it's reachable over on all other servers. That's what the config files are doing.

But the app actually has a wg tunnel inside another wg tunnel. If you (on Linux) run `wg` (as root) in a terminal when it's connected with multihop you will see that it has two peers set up for the `wg-mullvad` interface, one peer is routed through the other.

So the only thing that SE4 can see is encrypted WireGuard traffic headed for NL1.