There are three issues here, not one:
When you obtained valid ESIGN consent from each borrower (individually), you gained the legal right to treat e-documents (only the kind described in the pre-consent disclosures and tested as part of the ESIGN consent) as if they are paper. Provided you have followed the methodology tested as part of your ESIGN consent, you're square with ESIGN and the e-docs containing the CDs are legally "written."
Second issue: By delivering an ESIGN-compliant tree-free "written" CD in a timely manner, you are square with the delivery requirement of Reg. Z. Assuming the content is complete and accurate, you have no exposure up to this point.
This third issue has nothing to do with ESIGN. Compliance with Reg. Z's receipt requirement is subject only to the applicable parts of Reg. Z and related OIs. As Randy advises, systemic inadequacy or failure of your receipt mechanism creates the same unlimited exposure you would face if you failed to obtain paper receipts from both borrowers.