Can I add User Text to geometry inside existing blocks

My definition references blocks and figures out some geometric properties of the geometry they contain (namely beam sections and lengths).
This is all figured out and works well. But now, I want to assign Keys/Value pairs to the geometry in the blocks, based on what the definition has figured out.

…is that at all possible ?
What seems even more challenging is that the geometry is inside a nested block ; therefor, there are no actual instances of the block containing that geometry in my model.
There are just blocks containing blocks containing the said geometry.