Those polygon offset values have been in effect since forever. I currently have the same ones in my conf.ini. But this does not cure the flicker seen at moderate and long distance caused by surfaces in plane with the terrain.
Many objects have as the farthest LOD a very simple, flat texture placed at zero height. From sufficiently far away, this texture sitting on the ground suffers 'Z-plane fighting', if you will, where the texture and underlying ground texture battle it out to see who will dominate.

I've made a start on fixing this for a number of objects, mostly the more common ones used on Pacific maps. In most instances, it involves lifting the zero-height texture to that which is characteristic of the upper part or top. It is wonderful to fly over a city or town or busy airfield and no longer have a scintillating constellation of flickering buildings.
For these objects, and some others not suffering this issue, I've fixed collision boxes and fixed/added shadows
There are still MANY objects to tackle yet. I should issue an interim pack of those corrections and fixes dome thus far...