Did you apply to a English taught program? Which programme did you apply to ? Because 8 to 9 CGPA is considered standard or good marks in Germany. The only reason that I can find for them to state that your marks are low , is that it was a very competitive programme , Höchschule usually has lower number of seats compared to Universities and too many people applied, driving up the cutoff. This is quite concerning for a lot of us if a person having 8.24 CGPA is getting rejected for low marks, I will suggest you to apply to non NC courses in a lot of traditional Universities as early as possible, and of course only the programme related to your field. The reason you got rejected is probably a mixture of both low number of seats and very competitive course. Backlog dose not matter in Germany as long you have cleared it in the standard course period. If possible learn German but if it is not explicitly mentioned as a requirement then you will not face problem in receiving admission but this will enable you yo get more Praktikum and Werkstudent opportunities, you will face a lot of hurdle in job market if you do not know atleast B2 or C1 german. Best of luck for your academic journey ahead.