Here we go.  Not necessarily the best sites or sources, but here is where I am aiming.  (The pencil trick is fine. 
 I was thinking of later scenes.  Diane is a natural witch completely unaware of her abilities.  She doesn't believe in magic even though she knows a LOT about Wicca.  There is a reason her languages were listed.)

General Powers 
https://www.lunasgrimoire.com/thirteen-powers-of-the-witch/
(These can be explained by coincidence or rational means.)

The more theatrical
https://youtu.be/wUB5qhWkvr0
These are what the coven will start to access once Diane is a part of the coven.  She already evidences some of these, though mainly the stuff that can be attributed to non magical sources - like her art.  Once she joins, everyone should choose 1 or 2 specialties.  This won't mean you can only do those two, just be better at those than the other skills.

Telepathy:  I think this one should be allowed within the coven on a voluntary basis working much like a cellphone (minus voicemail and texting).