How to attach a blind to a wall when I need extra clearance?
This may be barely more than a suggestion but I'll post it as an answer.
Rather than make little 1cm blocks, I'd use a strip of wood about 1cm x 2cm the same length as the blind's width.  You could buy a piece of molding or trim that's right, or rip a strip off a scrap of wood, or etc.
This way you can attach that strip to the frame at spots that aren't right behind the mounting brackets for the blind, and the screws won't interfere with one another.  Plus it will be quite a bit stronger and probably a better finished appearance.