Of note, according to both silver-cards.de and rpaladin974, the TCG seems to have gone with a more straight translation of “Divination/Prediction Princess” for Mieru’s cards. But no English name is confirmed. And a reminder, Sibyl was a place holder name we used, “Divination/Prediction Princess” or whatever they use is much more accurate than Sibyl.

Source 1: rpaladin974 on ebay.fr
Source 2
Source 3