Measuring the rigging angles and the balance tells you what they are; it doesn't tell you what they need to be. Flying the model will tell you what they need to be.

If your elevator isn't lined up it means that either the designer didn't bother changing his design after test flying (more common than you'd think) or your model is different than the original. Heavier, lighter, faster, different balance point, thrust line, etc, etc, or even that the rigging is different.

You are proposing to take a (presumably) nice flying model and adjust the balance point to a worse position just to make the elevator line up. IOW you want to make it fly worse so that it will look pretty.

You don't adjust balance and down thrust to get the elevator to a given angle, that's putting the cart before the horse. Instead you adjust the balance and down thrust so the model flies the way you want, then trim the elevator as needed.

You have a choice;

1. You could accept the designers balance point, rigging angles, and control throws as being correct.

2. Adjust some or all of those things to have the model fly more the way you like. Speed and Jennifer have mentioned a couple of points and you can google more extensive trimming methods (triangulation trimming is one example and there are others).

At the end of the day the elevator will be where the elevator needs to be. And that's the correct position for it. If it doesn't line up with the stab that's totally irrelevant.

The designer may have had the elevator close to lined up with the stab but if you've changed something like installing more power for example, or changing the balance point, then you should not expect the elevator to line up any more.

Dave H