Thanks to Azkedars help, you can now reset your flatlands lot to 3 different options:

1. The normal flatlands
2. the “tech-lot” with hollow underground and 5-block markers (like lot flat_c20)
3. a lonely island! (like lot flat_d20)

The draftlands lots can now be reset to the current kingdom lot equivalent! In respect to additional options for the flatlands, I will be looking for more different lot types to build. If someone wants to make a lot with an underground nether world from 0-60 block height, that would be a great thing to offer too.