The problem with polishing current era Lodge is exactly what you, or your friend, are experiencing - seasoning won’t stick. Depending on what was used to do the polishing, some of that material could very well be imbedded in the cooking surface. That will certainly inhibit proper seasoning. It doesn’t sound too appetizing either. Chuck that skillet in the recycling, or make a clock or wind chime out of it. It shouldn’t be used for cooking. Why do you, or your friend, have an issue with the naturally bumpy and unground current era Lodge surface? I have never had any issues with food sticking in any of mine. Regardless to what current urban myths portend, unground skillets pose no issues for cooking. As a matter of fact, Lodge and BSR offered unground skillets in all of their catalogs back through time. They were cheaper to make and sell that way.
Sanding and polishing the damaged Wagner #8 is a bad idea that will only complicate matters. Use a different skillet for stove top cooking, and use the Wagner for baking food in the oven. If you start grinding one part of the skillet, it will only make that part thinner, increasing chances of warping or uneven heating/cooking.
Keep in mind that two coats of pre-seasoning is all that is necessary to prep a pan for use. Six coats starts to get too thick. Don’t be surprised if the flax seed oil starts to flake or crack. Most people here will recommend you change seasoning oils. Canola, Crisco, or coconut oil work much better in my experiences.
