Its really annoying but what if i want to paste a hexagon I've got from the library of babel, or I saved one and I want to review it. 

You have to write the whole entire hexagon like 3255 characters.

That seems to be a Unity limitation and only applies to the web version. You should be able to copy and paste hexagon locations in the macOS and Windows versions that you can download.

Yeah in the app 100% works. Now you should try to make Image of Archives from the library of babel basically the canvas of babel where every image combination is possible. When you upload your image in the app it converts to numbers and that's the seed for the image.