3. What have you tried to fix the issue?
I am inclined to have 2 questions for each item, 1 question for the [5% Stufen] and another question for the Teilpr. (MZB). Is this the best approach?
4. Upload any forms or screenshots you can share publicly below.
An alternate design might be: All first questions (5% steps) on one screen, and the relevant ones for the second question on the next screen. Separated for minerals and organic, or even together.
This might make it easier for the user to visibly control a 100% limit.
Furthermore, there might be two design options for the elements: matrix--style selects, repeat group with fixed repeat_count or separate groups.
As the number steps are fixed (5%), a select_one (e.g. minimal apperance) or range type might be an option.
The design decision should esp. address userfriendliness and easy analysis.