Can documents be pushed back to a previous signatory to complete sections that were filled in improperly?

If the envelope was configured originally for either Markup or Collaboration then technically it could be routed back to a Recipient to update the field. However, from a perspective of a basic envelope that was sent to a Recipient who say added wrong information to a field, then that information is locked into the document and the envelope. You could and should "void" the envelope, copy the original and send the new envelope back to the Recipient. You may want to add a Note or a Tooltip so the instructions on what is expected in more clear for the Recipient.

If you send this type of document regularly then I would recommend looking into Markup or Collaboration as possible future ways to modify information on future envelopes.