With registration, ownership has passed to you. Check the status of the C-sheet.
If you are already registered, ownership has passed to you under section 4 GBG. What now matters is whether the property was actually taken over free of encumbrances or only with the agreed ones. A current land register extract shows whether agreed deletions of mortgage liens in the C-sheet have already been carried out.
If entries do not match the purchase contract, for example because a promised discharge is missing, you should have the handling checked promptly. The rank and sequence of registrations are often decisive in the individual case.