Allison Argent: No
Celeste: No, she has Angelic blood though and in her world Demons are just Angels that fell from Heaven. I don't know if you want to count it or not. You're allowed to if you think she could.
Magik: Full on demon here. Feel free to notice. Would you be okay with her being able to sense that Galatea has demon in her? She's shown an ability to recognize demons, which I assume is because she is one.

Celeste: Celeste is a little stronger than a base-level human and faster. She's also got some crazy emotions. Angels feel with their whole and since her body isn't angelic it's hard for her to contain. It can sometimes drive her crazy and emotions can overwhelm and take her. She also has time manipulation abilities. All here in her abilities section. The only thing is that her healing capabilities and such are restricted to her.
Magik: Magik's not really any stronger or anything. She's a demon sorceress with lots of black/limbo magic. She carries around a Soulsword which is the remaining pieces of Illyana's soul along with bloodstones that are the same (technically, magik is a demonic copy of illyana so she has no soul just carries the pieces of illyana's soul). Magik's also a mutant with the ability to teleport and can move +/- 10 seconds in time in EV.

Go for it with any of mine. The only thing is with Magik she can't be detected while in the discs she uses to teleport. Because technically the disc is instantaneous movement (step in one appear, appear on other end). So predicting where she comes out would be impossible. She can sense her immediately after she steps out of a disc, though.

Okay with all of mine so long as it's the minor ways you listed above!