I've found the way of falling off the edge of Fortuna

[KappaToWin]

Since there's not a physical wall and just this icy wind you can just go across it with the colission of the K-Drive.

Just speed into the edge of the map with a K-Drive, theres a line where the ground stops being detailed, if you dont manage to crose it just bullet jump after you recover to go through.

I've tried to stand below the ground with archwing but it looks like it keeps repelling me so i keep falling. At the end since you have just fallen it just teleports you back up there.

https://streamable.com/2zz0u