Steps to reproduce:
Put Orion in fullscreen mode.
Select Bookmarks → Edit Bookmarks from the menu (or type ⎇⌘B).
The bookmarks show up in a new window that floats atop the main window. This is good.
Choose a bookmark and right-click / two finger click / ctrl-click on it, select Edit from the popup.
I expect the Edit Bookmark window to show up.
Apparently, nothing happens, except the Bookmarks window loses focus.
In reality, the Edit Bookmark window shows up in Desktop 1.
You find it if you switch to it, and then use the app switcher to switch back to Orion.
I am guessing that all that is missing is a setting for that window to allow it to float atop a fullscreen window. After all, the Bookmarks window manages this just fine.
Orion, OS version; hardware type:
Orion is Version 0.99.113.2-beta (WebKit 613.1.12).
OS is Monterey, 12.3.1.
Hardware is a 2021 Powerbook Pro (M1 processor).