Hello.
There is no D or other high notes. The whole left hand keyboard is on one octave.
That's the way it is, there's nothing we can do about it. That's why, among other things, the accordion has had a hard time being accepted in conservatories.
It took the insistence and ingenuity of Pierre Monichon (an eminent accordion specialist and historian whom I was lucky enough to have as a teacher) for it to be accepted. Pierre Monichon had created, for this purpose and with the help of Fratelli Crosio, the harmonéon. It was an accordion with a left hand keyboard identical and symmetrical to the right hand one. One could thus, not only find other octaves, but especially create one's own chords and reverse them on demand.
Yours sincerely.
Dan