وَأُخْرَى بِمَعْنَى «مِنْ أَيْنَ» نَحْوُ: «أَنَّى لَكِ هَذَا»
In another use annā means 'from where,' as in: Where did this come to you from?
The question concerns not merely the current location of a thing, but its origin or source. Ayna identifies place in general; min ayna asks about where something came from.
Accordingly annā should not be glossed as 'how' in every occurrence. Both uses must be distinguished by what the construction and context require.