Add ventilation state to cover

Homematic IP includes an adapter for Hörmann garage door drives (HmIP-MOD-HO). This also includes the option of only partially opening the garage door (a side sectional door).
What is needed to integrate this functionality into the cover device?

For further questions, please do not hesitate to contact me.

is there a solution so far?

I think I want something similar or even the same. The cover state object for my roller shutter now has two states that reflect fixed positons: open and closed. It also has an attribute that reads the position in a percentage. The ‘closed’ state corresponds to 0%. Anything else is ‘open’. This does not correspond to the real world. There is a ‘fully closed’ state, which corresponds to percentages of 2 and lower, a ‘ventilation’ state, which corresponds to percentages between 2 and 18, where the slats are pulled further apart to reveal ventilation openings, and for percentages above 18 the lowest part of the cover starts to move up, opening the window to the sun.
It would be great if the state object of the cover could be customized to have more than two states, with customizable percentages and names for the state.