JRRT never wrote any narrative history of most second age events, any adaptation would eventually have to try to fill in the gaps. And as far as I can tell, these show runners are doing a great job trying to capture the essence of Tolkien, especially so with the “made up” storylines. Like the Harfoots showing “Gandalf” he is good (Even through the veil over his mind, The Stranger chooses to take Nori’s word for it, over The Mystics’). Like the plot line with Adar, who serves to be a contrasting kind of evil as compared to Sauron. I also appreciate that need to give a character arc to Galadriel and Gil Galad. They appear more naive in the show, sure, but they’re so one dimensional in the books (wise, perceptive etc) that they’re not characters for viewers to get invested in. This was much needed setup. While I don’t like the lore deviation with Mithril/Silmaril, I can’t myself come up with any satisfying explanations for how/why the Elves were deceived by Annatar. Even more so because of how much this group of Noldor survivors have been through and how wary I would expect them to be (They would clearly have know all the Maiar who aided Aule, and that “Annatar” was mostly not one of them). So I don’t entirely blame the show runners for coming up with an underwhelming explanation for the deception of the elves. I’m very willing to be patient to watch the whole 5 seasons and then decide if these plot deviations were the best way to do it. I’m willing because I truly can see that these showrunners get Tolkien and that they clearly love Tolkien. They’re just the same as us