As billd91 already said
...according to their own words, the showrunners are both forbidden to use material from the Silmarillion AND to blatantly contradict it! I can understand that this is an uncomfortable situation for the writers to be in, but I think they've maneuvered themselves on thin ice.
As I said previously, it's an impossible tightrope to walk. The only way that I can see them doing it is by being additive to the lore, rather than referencing it.
Yeah, even elf kings can be wrong. In fact, when you're talking about big mythic characters like these, the audience should expect huge mistakes, as we're currently barreling toward in Numenor.
The season and the series aren't over, and the estate apparently signed off on what they're doing. It's likely that things are more (and less) than what they seem at this point.
Oh, I don't know that it's quite that hard. And yes, being additive would be one way to handle things - and they've certainly done that with events in the local communities around the lands that will become Mordor and with the migratory Harfoots. Dealing with known characters could be harder, but the Second Age is fairly undetailed except for names of Numenorean kings and a few bits on the timeline (which, I might add, has been pretty thoroughly tossed out the window). There's room for a LOT of non-contradictory detail and drama.
Introducing new mysterious characters and having powerful characters showing unusual powers is very much in keeping with Tolkien storytelling. It happens all the time in The Lord of the Rings and The Hobbit.
Quite possibly factually contradictory, but contradictory to the spirit of Tolkien's work? Introducing a plot device that brings the mutual mistrust and divisiveness between elves and dwarves into sharp focus so that we can explore it within the course of a single show is good storytelling, and very reminiscent of the Arkenstone sharpening the divisiveness driving the disputes between dwarves, men and elves over the Lonely Mountain in The Hobbit.
Do all elves recognise each other by sight?
I'm thinking of it from the standpoint of having to know all the material that you can't use, so that you don't contradict it, but you also can't incorporate any of it in the final work. "Impossible" might be over stating it a bit, but not a lot.
Not what I recall, but I’m sure someone with a less hole-ridden memory can tell us if there is anything.
In Unfinished Tales Tolkien places the two Blue Wizards in the Third Age along with Gandalf, Saruman and Radagast. They are named Alatar and Pallando.
