I like your site . It is fast on desktop and mobile. I have to agree with Suzuki, try to underline or put some marker on the most important lines. When you scroll donw, you can lose yourself in the text.
I can give you a proposa, why do no you add English version as well. I know most of the people in Germany are very good and almost native with English.
On the rigght side-bar there is too blank, empty space. Eye of the customer has to see something and to be attracted, not to feel like getting lost
Seven times fall, eight times stand.