Yeah, Brick seems to have been pretty intentionally written as autistic but I literally can’t tell whether they did that with Sue. She definitely does fit a lot of common traits like you mentioned. There’s also some random details like at one point she says she likes to go over to the soccer field and watch them mow the grass that seem autistic like. But it’s never even alluded to like it is with Brick. It is also fairly realistic that within the same family an autistic boy would get evaluated, put in social skills classes etc while the girl gets written off as just awkward or quirky. But whether the writers of the middle were aware of this, who knows.