There was a change in the prohibition and at this time it is allowed for just one time and only for the whole property, meaning that if you have an old "carta constancia" you can convey it whole (not a piece of it) to the buyer without a deslinde. Of course, the buyer would be assuming the risk that the property is not where he thinks it is within the parcel of land. Also, the buyer will not be able to sell it in the future without a deslinde.
Condo units in condominiums built on properties without a deslinde before the 2005 Land Registry law can also be conveyed without any problem.