Complex sentence: Just after the book's release, he got cold feet about releasing the personal details about "Nina" and asked Dagmar to buy up every copy she could find... she did and managed to acquire most of the 5,000 copies that had been released.
Split into simpler sentences: Just after the book's release, he change his mind about releasing the personal details about "Nina" and asked Dagmar to buy up every copy she could find. She managed to acquire most of the 5,000 copies that had been released.