This different-from-other-area-effects SA question came up in a RAW/RAI FB group: in the following pic, if the template for Thunderwave is applied as per the gray zone, are all squares X’d affected by the spell? Only squares that are at least half covered.
— Dan Dillon (@Dan_Dillon_1) July 22, 2020
At our table (a virtual table) the standing rule is that if the center of the square is inside the template it is hit. We have an understanding though that min maxing template placement is not good play and it rarely comes up.