Hi Fredric,
I too, experience this same loud noisy fan after windows recent update to my Surface Book 2. As you have done, I rolled back the updates and went to a previous restore point.
Unfortunately I couldn't keep from the window update forever and felt forced to install it. I rolled back to another restore point, this time it didn't translate so well and ended that Windows OS with a blue screen error and wouldn't load up at all.
I have since installed a brand new Windows 10 OS, reinstalled all new apps and video card driver to my Surface Book 2, and as well as the most recent windows update. And have the LOUD NOISY FANS still. It's like the fan speeds have been increased by 10 surface book 2 isn't even running hot. Hope Microsoft looks into this and updates the remedy to their creation.