I used to have a girl friend that was a Tarot Card reader. I know how it works. I have seen people absolutely amazed that she could "read their mail" this is what the demon spirit helped the girl do. There is no doubt that the demon spirit gave her an uncanny way of knowing things. This however would not be the kind of foretelling of future events that God is talking about only he can do.
The Holy Spirit will not say one thing in Isaiah then contradict it in Acts. We have to make them reconcile. How do you reconcile that the ability to declare the future is a Divine attribute in Isaiah and not one in Acts. You can't. You must conclude that the girl lost her ability to say those things that made her creepy, like maybe telling someone where to look to find a lost coin in their house. Or which house their wayward son is shacked up with a prostitute. Things that made her of reputation as a fortune teller that was indeed real but not the Divine attribute of being able to really tell their future. You cannot ignore Isaiah 41 in your interrpretation.
There is absolutely no knowledge you can have about what they see about the future in the spiritual realm from any scriptures we have discussed so far. That is just some guess about the way things might be in the spiritual realm on your part.
At this point I think you should concede that Isaiah 41 must be taken into account and that you agree that this girl could not actually tell the future because only God can do that. You could word your concession something like...
Scribe is correct and I concede that... Or you could skip that part and just agree that we must include Isaiah 41 in our interpretation.