Generally speaking, the Orion and Orion RC bookmark bars are nearly impossible to edit. I just upgraded from Orion to Orion RC; I'm on a Macbook Air, Apple M1 chip, running on Sequoia 15.6.1. When I started setting up Orion RC I imported bookmarks from Orion and Safari. All of my bookmarks showed up in the bookmarks bar - most of which were not in the bookmarks bar in Orion or Safari - including all of my bookmark folders, which I kept only in the bookmarks pull-down menu.
So I had to search for info on how to delete items from the bookmarks bar because it is not intuitively obvious. Once I got rid of the items I don't want in the bar, I tried to rearrange them to the order I prefer. Dragging icons to a new spot in the bar seems to work, but with every move Orion RC (this happens in Orion as well) scrambles the icons - so I'll have the Wikipedia URL attached to the Squarespace icon, for example. I currenlty have three icons in the bookmarks browser that are doubled or tripled, with all but one of the duplicated icons attached to the correct URL.
I have tried quitting and restarting the browser - doesn't really help.
Screenshot of my bookmarks bar as it currently looks. I like the bar to show icon-only, no text. You should be able to see the duplicates. For each duplicated icon, only one is attached to the correct URL.

Importing bookmarks: I expected the bookmarks to go where they had been on the previous browser (Safari or Orion) - bar items in the bar, pull-down folders in the pull-down menu, etc.
Deleting superfluous items from the bar: I expected this to be easy to do. In Safari there is an "Edit Bookmarks" item in the Bookmarks tab for the browser. That is much easier to deal with than having to do a right click on a Mac (Option-click).
Rearranging icons in the bar: I expected the icons to stay attached to their respective URLs. I don't understand why this random scrambling of icons happens.
Orion Plus version 0.99.137.3-rc (WebKit 623.1.8.0.0); Sequoia 15.6.1
Sequoia (15)