"Incorrect" in that SRB2 pushes all of its sprites up by 4 pixels for whatever reason, so even if it looks correct in SLADE and Zone Builder, they're misaligned ingame, enough that the top spike in the comparison image below extends above the platform it's attached to.
Zone Builder vs ingame - note that the spike mobjs themselves are in the same position.
Zone Builder vs ingame - note that the spike mobjs themselves are in the same position.