It looks like the arrow rest on the Martin Saber is fully adjustable, so I would rather see you adjust it to an optimal position for arrow flight rather than use it to move your POI. That position would be where the center of the arrow is just outside the centerline of the bow. If you have a pickup truck handy, the tailgate makes a good stand to adjust the centershot. Prop the upper limb of the bow against the open tailgate with the lower limb tip on a pad or something on the ground. Mount an arrow on the bow and stand behind it with one eye closed so that you can line up the string with the centerline of the bow. Notice where the tip of the arrow lies with respect to the string; if it isn’t just outside of the string, adjust the arrow rest until it is.
I’m not worried about your high misses, since you say they are consistent. You’ll learn to control those with time, whether you aim instinctively or using a reference point, like the arrow tip.
Your left misses could be due to any number of form issues, or could be due to the spine of the arrow or the strike plate. Since you are shooting off a rest, you probably don’t have much control over the strike plate, unless you decide to start using a cushion plunger. If you want to stay strictly trad, you should probably figure out how to solve the problem without a cushion plunger. You can try different arrow spines, or try changing the length of the arrows a little. Normally, changing to a weaker spine or longer arrow length would be the most likely to move the POI to the right; however, sometimes the opposite works too. Sometimes changing the brace height can effect POI as well. I don’t see any reason why you shouldn’t experiment with these things, realizing that your form might change and then you’ll have to start experimenting again.
My experience with my students and myself is that as form improves, the groups start moving to the right, although YMMV. I assume you are a RH shooter?
Obviously, as you stated in your second post, you shouldn’t draw any conclusions until you feel okay.