Completely broken:
- blueprint does not work outside of a combinator to create a schema once and reuse it as part of other, larger schemas. Ignores small combinators for the blueprint tool.
- If player mine the combinator, it returns only one (circuitissimo): it does not return the variants of small as large back to the inventory; or it does not remember the circuitissimo combinator schema in the item tags (or something) — to re-place it on the surface with already installed small combinatiors inside — how it works with "packing tape" mod.

Could you fix it, or can we pick the mod up and fix and extend it?

Blueprinting in general is pretty whack, man.
Making blueprinting work "properly" would take re-engineering everything to pull off a number of really jank tricks to make it work as someone would generally expect.
Main issue is tags are not stored in blueprints, so you can copy settings, and may be able to directly copy/paste, but you cannot save them into blueprints. You would instead have to blueprint the interior, much like a factorissimo building.