Upon learning that Syria’s dynastic dictatorship had fallen, Iman Mohammed, a Syrian refugee living in Germany, felt a surge of elation at the idea that she could return to her homeland. But that joy quickly faltered as another thought occurred to her: Going back to Syria could mean giving up everything that she and her family had built in Germany since making the dangerous trek to arrive there nearly a decade ago. “In the cold light of day, when we really looked at everything that had happened, we realized, not just yet,” Ms. Mohammed, 41, said of the idea that...