Hello @WS J,
It obviously depends on the weather as if it's too cloudy or if the visibility is too low, you won't be seeing them below the cloud/low visibility layer.
Now, Weather add-on is being use. (Active Sky in Use)
Are you saying that the aurora or the Milky Way may not be visible depending on real-time weather?
The Milky Way comes out as shown in the picture,
it's picture a Envtex applied normally?
Is there any way to make Aurora and the Milky Way brighter?
please refer to attached set-up photos and screenshots