So... is this before or after they go to Gensokyo?

A refridgerator with electricity, in a temple, in Gensokyo? And why would Sanae be wearing a school uniform and carrying a plastic sack in Gensokyo? Would there be a village near enough to the temple for her to buy groceries?

The level of technology is all over the place in Gensokyo, especially in fan work. She could have brought her uniform with her and either likes to wear it or could be enrolled in Keine's school for whatever reason and wears it there. And dropping by the Human Village is no big task for someone who can fly. She could also stop by while on the way home.

For that matter, there are no tengu in the real world, so they're in Gensokyo.

Y'know, there's a simple explanation to this:
"Modern Gensokyo"