What patterns, exactly, did you try?
I would have started with
Include: C:\Users\:\AppData\Roaming\Thunderbird\*;C:\Users\*
Exclude: C:\Users\:\AppData\*
If I then found the Exclude was preventing the Thunderbird backup, I’d look at 8.3.5 Virtual sub client names, which is a way of having multiple backup jobs defined for a single client. This lets you schedule different directories for backup on different schedules, or, as here, include files that would otherwise be excluded by the main backup.
As the Administration Manual is short on examples, here is a forum post covering much of what you ask.