Actually, it sounds like the Tesla 19" wheels with the covers will be about the same weight or maybe slightly lighter than the Tsportsline wheels. In the Daerik video, he weighed the complete 19" aero wheel/tire combination, and it was .8 pounds heavier than the stock 18" aero wheel/tire combination. The stock 18" wheel with aero covers is supposed to weigh
23 pounds. The Tsportsline wheels weigh from 23.7 to 24.4 pounds. The primary advantage I see to the Tesla wheels is the aero, so there should be no reduction in range versus the 18" wheels.
Also, I seem to remember hearing somewhere that the stock Model 3 wheels are flow forged, although I can't find that now. Still, it wouldn't surprise me if many of Tesla's wheels are flow forged; it's an excellent compromise between strength and cost, and Tesla is usually pretty good about that sort of thing.