HaLeiVi: That’s only because of our Chisaron Yediya as to what the Maskana of the Gemara was. There was one way that was given at Sinai and any other way is Passul. This isn’t somewhere where it’s Shayach to say Eilu V’eilu (unless you say like the Rambam about Machlokes, which I don’t think you do).
I don’t know what “Inyan” means, but presumably it means that there is something to be learned or some additional mystical component to the Mitzvah. So I repeat, it’s not Shayach to have an “Inyan” that is relevant to the wrong way to put on Tefillin. There was one order given to us at Mattan Torah. Unfortunately, some of the Rishonim (we assume Rabbeinu Tam and the Shimusha Rabba) were not able to properly be M’chaven to what the order was based on the Gemara. One of the orders mentioned in the Rishonim is definitely a Passul order. There is no way around that.