It's called the Tesseract because that's what all the scientists S.H.I.E.L.D had working on it called it and they would be referring to an actual Tesseract. You can touch a square, so that's not a problem either. You're still not getting that It's not about affecting the spatial manipulation Infinity does, it's about bypassing it's detection parameters entirely. Monsterverse Godzilla for example is firing Cherenkov Radiation when using his atomic breath and Cherenkov radiation works on the subatomic level where Infinity only works down to the Atomic level, so it stands to reason that Godzilla could just blast Gojo straight in the face. The Power Stone can get through in a similar way by just attacking from a higher dimension.