More photos - ideas, please.

I think what I might do is leave the redwood beams exposed and unpainted, but paint the planks in between white. Otherwise, you'll literally have to scrape out every crack between the planks. Not sure it's worth the time and effort to do that.

I like the old paint peeking through. When you get up close it's not beautiful, but in context of the whole space, and with the brick I think it's perfect. In Europe this would be the norm in older spaces being restored. I love your house !!

This might be too painful but could you paint the caulk brown? Once the ceiling gets stained or clear coated it would blend in?