Philadelphia’s new and supposedly improved property values, heralded as the solution to a broken tax system, are so filled with errors that it may take up to two years to get them right, according to the city budget director. Despite a $7 million computer system, payments to experts, and years of staff time, the proposed new assessments are nowhere near ready to go out on tax bills, said Stephen Agostini, who has been leading a review of the new numbers. Lee mas…