If true, perhaps the Shadchen did her a favor by being blunt despite the hurt feelings. Now go help your sister with her wardrobe if there’s truly something to fix. If she’s simply dressing “eidel” good for her, but try to look for a more ruchniyusdig boy.
As a famous Rebbetzin once said, Shlomo Hamelech said Sheker Hachein V’Hevel Hayofi, but 1) he was the wisest man ever 2) he had many wives before he figured that out.