I tested this, and you're right, not looking always goes to the Sy end. But if I remember correctly (which I probably don't, I have a terrible memory) there's a certain part of an ending (I forget which, maybe the Butterscotch one) where Sy looks but doesn't tell Pastille she knows. So maybe she's acting like she doesn't know in the comics? I don't fully assume the comics are 100% cannon either though. My best guesses are the Gumdrop and Butterscotch. Either way I guess it doesn't matter too much?
1."Sy looks but doesn't tell Pastille she knows" Yes, you're right. There is such ending. I checked the game, it's in the Gumdrop's ending, the Butterscotch's ending and the Toffee's ending. But in the Gumdrop's ending the candy girl travels with Syrop over the world, while Pastille runs the store. In the comics you can see that it isn't the case. As for the Butterscotch's ending, in said ending Syrop doesn't hide her recepies and it isn't the case in the comics. And as for the Toffee ending, in the comics Syrop doesn't look to enjoy her company very much.
2."I don't fully assume the comics are 100% cannon either though." In game "Wandering wolf Trick" you can meet with Pastille and Syrop. If you talk with Pastille you can figure out that either Syrop still doesn't know or she pretends she doesn't know that her assistent can do magic. And I think Syrop still runs her business because in all endings where she is out business Pastille left Syrop forever. I think we can also exclude possibility that Trick met them before Gumdrop was created because in the Toffee's endings we can see that Treat lives alone (instead of with Mochi) in a permanent house (instead of an igloo). In other words, Gumdrop was created somewhere between "Lonely wolf Treat" and "Friendly bunny Mochi". "Wandering wolf Treat" happens latter than both of them, when Trick arrives Mochi already lives with Treat. Thus when Trick met Syrop Gumdrop probably already existed. Thus if we ignore the comics it leaves us with Toffee's, Butterscotch's and Gumdrop's endings as alternatives. Otherwise there is only the Syrop's ending.