I understand the idea of {} that you talk about, but I don't know how it works in the context of logical reasoning. Can you give examples on how it interacts with the other 4 values under different logical connectives?
I think there's something similar at play in physics and in the real world.
Can only explain with a (likely flawed) computing metaphor: "the value is a pointer that you cannot dereference but opaque sub-systems of your mind can still compute stuff with it (eg. it's not truly unknown)".
If I'd try, I'd say that: there's stuff you can indirectly compute with but can't express logically or communicate in a logical language.