Let us compare hitting a golf ball with shooting with a rifle. Golfers’ incapability to control the sweet spot precision can be compared to a ramshackle rifle. No matter how good the shooter is and no matter how precise he targets (aligns the angles of the rifle to the target), with a ramshackle riffle he will always be imprecise because the bullet leaves the barrel in a randomly different way.
To accurize a ramshackle rifle can be a very difficult task and can take a significant amount of time; the barrel must have an absolutely uniform dimension (to a ten-thousandth of an inch) for the length of their bores in order to be accurate, and, there are other factors that might need to be worked on. However, once the rifle is accurate, it’s all downhill from there.
You take the improved rifle to a shooting range and although you aim precisely using scopes, the bullet might repeatedly miss the target in one direction. You adjust the scopes accordingly (angle of the barrel in relation to the target) and now the bullet hits the target every time.
Similarly, adjusting the club face angles and swing path of a golf swing is really a piece of cake in comparison to mastering the sweet spot precision.
So, you should not worry if the swing path or club face angles are one or two degrees off while committing your full attention to the sweet spot practice using the groover. The optimal scenario is that you combine your groover practice with that on the range. For example, during the week you practice at home on the groover, and then on the weekend, you go to the range. There you can fix any face/path discrepancies you notice and then bring the adjustments to your groover sweet spot practice. In this way, the discrepancies will be minimized and become negligible.