I've been using Microsoft David for a while, and on my machine, with no speech dictionary tweaking of any kind, the word moreover is pronounced exactly as I'd expect, like more and over with no pause between the two words.
Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763
Puritanism: The haunting fear that someone, somewhere, may be happy.
~ H.L. Mencken