Would it be possible to make the position of the fancy armor stands more precise so that they are also possible at a 45 degree angle

Hi, unfortunately that is impossible due to how the armor stands are implemented (that is, as blocks, not as entities). It would also be visually jarring to have a full-block square base suddenly be rotated at a 45 degrees angle.

As such, I'll kindly have to deny that request. Thank you for suggesting anyways!