"auch wieder nicht", is a mix of "auch nicht" = "not either", and "wieder" is repetitive (="too/also") for an implied (but not actually mentioned) earlier statement. So in this context "selbst ... have recognized" is some kind of laurel on them, but the "selbst = even" is putting that positive statement into the negative, implying that they are actually quite dump. "ganz dumm sind sie nicht = they are not entirely stupid", "ganz dumm sind sie auch nicht" = neither they are entirely stupid", and "ganz dumm sind sie auch wieder nicht" = "but again, they are not completely stupid either" I think DeepL is performing very well here.

"Auch wieder nicht", is a mix of "auch nicht" = "not either", and "wieder" is repetitive (="too/also") for an implied (but not actually mentioned) earlier statement. So in this context "selbst ... have recognized" is some kind of laurel on them, but the "selbst = even" is putting that positive statement into the negative, implying that they are actually quite dump. "Ganz dumm sind sie nicht = they are not entirely stupid", "ganz dumm sind sie auch nicht" = neither they are entirely stupid", and "ganz dumm sind sie auch wieder nicht" = "but again, they are not completely stupid either". I think DeepL is performing very well here.