I can totally identify with your reactions. One suggestion would be to follow up with the teacher for more info. - i.e., get the teacher to articulate any concerns related to her comment about Hanni's intelligence. Hanni may well start to hide who she is, and you should be on the watch for that. Many here can give you advice on that. But I also wanted to add that she may never do that - every kid is different.
My only kids are 12yo twins who are both "really intelligent" (and teachers (at our kids' professor-spawn school) still say that to us too). But my kids are also still the middle school equivalent of the "gooey messy shrieky fun" kind of kids as well. Our kids are now finishing up 6th grade in the neighborhood public school, and have not had grade acceleration. And while they could have benefited from more advanced curricula in some areas (they are in 9th grade math, but that is their only subject acceleration), they are having a blast and are very comfortable with who they are. We feel very fortunate that way. (They both just started online courses in areas of personal interest through NUMATS, so we're doing a bit of enrichment.)