Import previous version of a Project from a backup of the Library?

I have an FCP Library open and I edited a project. I want to go back to an old version of that project in a backup of the Library.

I don't want to restore the old Library and lose my work from today.

I tried this:

Inside current Library in FCP:

Duplicate the current version of the project. So now V3 is copied to V4.

Delete V3, the version I want to go back to an old copy.

Close this Library.

Show package contents on both Libraries.

Open the Event in question.

There's a folder named after the project, V3, that I want, which is the old version. There's an .fcpevent file inside the folder.

Copy that folder and contents into the Current Library.

Now I open the Current Library again, and the V3 Project doesn't show up.

What is the proper way to restore a backup of just one event?

And to do so without copying all the project media multiple times into various places...