It does not look good, you will not be happy with it in the long run. You have hired a quality contractor at quality prices and should not accept that kind of work.
With the steel away from the wall you are providing a home for insects and jingjoks which will get messy and become a cleaning problem in the future.
Unless there is something that mounts on the steel which will hide it all.
I do not think you need a measurable standard, just looking at it should be sufficient for the contractor to understand it needs to be corrected.