Cardbook is a separate product: some like it, some don't. So, technically, cardbook data interferes with Thunderbird contacts, not the other way. Thunderbird does provide listing of addressbook by pressing the F9 key. If you sense that Cardbook and Thunderbird are not working well together, I encourage writing to the Cardbook author. Thunderbird addressbook does handle groups, so it may help to share what feature you are valuing in Cardbook. I mention that, as I have seen several situations where Cardbook was causing difficulties for users. Thank you.

I use Cardbook, synced with Google Contacts. I agree that it's kind of inscrutable, and the documentation is useless and I wish there was a user forum. But I like the advanced features, so I keep it even though parts of it are hard to get my head around.

See the attached image showing my Cardbook settings - notice that "Unique source for contacts" in effect disables the Thunderbird Address List, though it's still available.

One major confusion is really the fault of Google Contacts. It does not support Mail List groups as we usually think of them. Instead, use Categories (a.k.a. "Labels), which can then be used like a Mail List, that is, you can address a message to the Category name and it will populate the field with those contacts. Note that the Thunderbird Address Book is similar - you can't create Lists in a synced Google address book there, either.

You can make more conventional Mail Lists with Cardbook, but only in local address books. I find them to be of more limited value. For one thing, they can only store email addresses, not the "friendly name" or other contact info. They can alternately store complete contacts, but those can't be used to address a message, so what's the good of that, I say.