The problem is that the guitar is too right-shifted for me. The problem is worse when the strap button is at or near the bridge.
This is not unlike my bicycle seat being too high for you.
With cycling, a fit specialist will adjust the bicycle to the cyclist’s body. This includes changing the heights and angles of the seat, seatpost, stem, and handlebars.
Bicycle fit specialists make adjustments to make the cyclist more comfortable on the bike, to eliminate arm, back, neck, knee, and hip pain, and to improve efficiency, speed, comfort, and power.
In contrast, guitar players get to pick a body design and a color.
This works well for most players, as the instrument can be moved around. But when you have very broad shoulders, as I do, or a very flat breastplate, as I also do, and very long arms (I don’t have this “problem”, unfortunately), the guitar fit can be a problem.
Fit problems can also arise for smaller people, such as young children, who may be too small to play certain things on their instrument well or at all. This is also a problem with the piano.
The problem with custom instruments is aggregated with the unknown effect that any particular cut might not be easily recut. Some things, like strap buttons, can be moved. Other things, like the angle or shape of the body or the pitch of the neck cannot be easily or heavily changed once built. Once the custom guitar has been built, it’s built. If it doesn’t balance like you guessed it might, too bad. You’re stuck with a weird guitar that doesn’t balance well. Happy expensive experiment. Better luck next time.