One thing to ask. Is this report card the same as what would be sent to another school if you were transferring/applying. In H.S. the report card in NOT the same as the transcript. Report Card has comments on it & more detail, while the transcript is just end of semester grades.

While I don't think they shouldn't refer to the 504 in the report card you might want to check if this report is just for the parents/guardian and not what other schools will see.