Mmmm, very strange. I must have something missing somewhere along the line, as my only Clover boot option once the installer is complete is my normal 'MacOS Drive' which is the original drive which has my fully-working Mojave 10.14.6 installed on it. I never get to see the 'MacOS Drive - Data' boot option, even when pressing F3 in Clover. Just to confirm, the 'Data' drive is actually there when I boot into my cloned Mojave drive, it just doesn't appear as an option within Clover (v5070).
I don't really have time to sort it out at the moment but your excellent build thread will help a lot when I do, so thanks for keeping it up to date!