"Can I sleep?"
Translation:क्या मैं सो सकता हूँ?
Why the variant मैं सो सकती हूं is wrong if the person is female? Then specify in the question that its for the male.
It might be because you used हूं instead of हूँ. When there are no other diatrics on top of the line, you cannot use the dot in place of the moon-dot.
However, the more likely reason is that the alternate translation has just not been added yet. You can report it if you encounter the sentence again.