Cassandra speaks a few sentences from Patroklos, her 2P is basically the colors of Pyrrha's 2P, let's not even mention the Deucalion that everyone thought would be the "new patroklos", but it was actually another reference to Pyrrha.You're right, but we will see! BTW Rock, Natsu, Xiba, Leixia, Algol and ZWEI haven't got a reference by a character in the game.. For example: Rock-Astaroth, Natsu-Taki, Xiba-Kilik, Leixia-Xianghua, Algol-Azwel, ZWEI-Groh.
Lingyu's sister's name is L-E-I-X-I-A, Xianghua has a similar passion for mooncakes but less exaggerated than Xiba's steam buns. Maxi COLOR 3 & 4 are basically Natsu and Xiba, lets not forget Mi-na COLOR 4, who is another reference to Xiba.
Astaroth profile mentions he is similar to White Giant (Rock), you also could note he looks more "barbarian" than "executioner" appearance.
Wilhelm basicamente use somehting similar to Z.W.E.I. 2P, There are several references not just the colors of their alternate costumes.