How to use Variants for a Custom Board

[SetZero]

Hello,
I'm currently trying to get a new board working in zephyr, where I want to use the variant feature to have multiple soc of the same type.
As described in https://docs.zephyrproject.org/latest/hardware/porting/board_porting.html#write-your-board-yaml

My board.yml looks like this:

board:
  name: mydemo
  vendor: myname
  socs:
    - name: somesoc
      variants:
      - name: main
      - name: backup

But this fails every time with, the following error when building with west build -b mydemo/somesoc/m7/main:

    ...
    File "/zephyr/scripts/list_boards.py", line 85, in <listcomp>
      [Variant.from_dict(v) for v in variants if c == v['cpucluster']]

  KeyError: 'cpucluster'

It looks like it is trying to get a nonexistent key cpucluster from variants, which is a list of key value objects, none of which are "cpucluster". I do use cluster m7, but I don't see an option to add this to the yaml. Removing the "if c == v['cpucluster']]" check yields other errors, so this seems to be some deeper issue. When I remove variants everything works as expected, but then I only have one SOC for my board

Now my questions are:

• Are variants supposed to be in that way, to define multiple SOCs of the same type but with slightly different config?
• Is this a bug, not fully implemented, a user error or are variants supposed to be used differently?

Thanks in advance!