Re: Is there any difference between "appear in" and "appear into"?
I agree- in BrE Appear Into is unnatural.
He appeared in the doorway..... that's fine. He appeared into the doorway...... Not good. He moved into the doorway..... OK .
The stars appeared..... doesn't need any preposition.
He appeared from behind the screen...... opposite idea of movement.... If you are explaining the location, as konungursiva said, then use an extra word. The word appear often needs no extra word.
IN your star example, if you want to say ... into view.... then: The stars Came into view.