Tagged for $18 million on a guaranty that included a “guaranteed principal amount” of $7 million — plus any “accrued and unpaid interest” on $22 million in loans from First American Bank to the partnerships that owned the building at 1000 S. Michigan Ave. in Chicago — three guarantors (John, Edward and Richard Borkowski) argued a Cook County judge erred in ordering them to pay statutory post-judgment interest of 9 percent per annum (under Section 2-1303 of the Illinois Code of Civil …