I was under the impression it was automated, because Ian Leyland was explaining the stuff about the deliberate height of the building foundations to be able to procedurally distribute them onto terrain and avoid them floating… maybe I assumed it is part of Procedural Planet Tech already. Sadly for you it is not. I hope you will get it soon to ease your life. Must be painstaking to adjust everything manually.
Just finished bug week on the art team for 3.12 and at least as of Friday this issue is fixed!