After letting out the High Bishop's robes, she mentions that they still cover her legs completely, but makes no mention of having to hike it up to not trip on it. And that robe was made to acommodate her expected height for the entire tenure as High Bishop, which was always intended to come to an end at 15, when she comes of age.

So regardless of what Erwaermen and Anwachs intended, her looking close to her actual age was certainly the outcome.

But you do make a good point. Since we don't know the full intent of the gods, we can not assume that she now looks exactly 14, just because that's her true age. We only know for certain, that she still fits in the HIgh Bishop's robes. But since Corinna couldn't just measure how tall she would be in the future, she could only have spitballed it. So the robes might have ended up either a bit too small or too big for Rozemyne, once she came of age, they might have incorporated some extra safety margin, or not... plenty of fuzzy factors that might shift her current apparent age one way or the other, but only to a certain degree.

I think we can still assume she now looks something within the 13 to 15 range with a high degree of certainty. I guess we'll know more, once the comments start rolling in from the other nobles, and once Rozemyne can see herself in a mirror.