For help to others, actually found where they are stored now by pure luck.
If you do a Ctrl + O = Open and look at Path Maps > UserData: Profiles > Default > User.fu
You need to have "All Files (*.*)" selected in the dropdown to see it.
C:\Users\You\AppData\Roaming\Blackmagic Design\Fusion\Profiles\Default\User.fu
Right Mouse Button click and open with a text editor,
you'll see that your hotkeys will be stored there.
Gonna make a copy of this file in Dropbox...