As this thread is related to the latest features of cardano-signer, i will make a reply here.
Cardano-Signer v1.29.0 or higher now fully supports the key resoration for old 12-Word Byron-Daedalus DDz… addresses and 15-Word Byron-Yoroi Ae2… addresses. In case for Daedalus, a auto-derivationpath decryption feature was implemented.
You can checkout the release notes with usage examples here: Release cardano-signer 1.29.0 (Byron-Edition) · gitmachtl/cardano-signer · GitHub
Some command example can also be found here too: How to claim midnight NIGHT tokens for old Byron Daedalus/Yoroi wallet funds - Tutorial