...
maybe, it might help, just
ignore the hatch objects ...
because it is probable (not sure) that the hatch is
contained in plines or lines, arcs ...
...
you would need to develop your own getboundingbox function by analysing the hatch boundary within the block definition and transforming accordingly to account for the position, scale, rotation, and orientation of the block reference.
...
For this, someone told me, to ask to a great Lisper (and not only)
that lives in London ...
...
anyway, I'll give it a try ...
...
thank you, for
your great work !
...
ciao