Do we even really know how lucid Barb is? I legitimately don't know if she even realizes what's happening or what's happened to her. She clearly has dementia.
We genuinely don't. We can only really judge what we see from the videos that CwC has of her, and from those alone, she's almost never lucid.
There is a theory that its all a fake out on her part, to portray herself in a more sympathetic light when she needs to e-beg with Chris, but I would say that seems doubtful.
From all we've seen of her, she has never seemed that in tune to what the internet is, or how the donations necessarily work. She also doesn't seem like the smartest person overall, and I think her personal history outside of CwC kind of reflects that with how trampy she is.
A long term psy-op, and pretending to be dementia ridden for months whenever a camera is filming (and with Chris chan around, you literally never know when the autist is filming) seems beyond her.
She also seemed to haughty and proud in previous videos of hers from the
good ol' days. I'm sure that she has moments of lucidity, but I think if she was faking her potential dementia, she'd do so in a, less humiliating way I guess?
Long story short, best guess we have is that she is rarely ever lucid, but we can only really judge by what we see of her and what we know of her past.