Maxperson
Morkus from Orkus
Well, [MENTION=6787503]Hriston[/MENTION]'s answer is "no" - lightly obscured may or may not make you not seen clearly, depending on whether or not a Perception check (if required) succeeds. But if a person is seen despite light obscurement - because any required Perception check succeeded despite disadvantage - then they are, ipso facto, seen clearly.
Yes, but the reality of language says he is wrong. Someone lightly obscured can be seen, but not clearly. "Obscured" and "seen clearly" are mutually exclusive circumstances. One cannot be both at the same time.
Hence Hriston's view that, in a case where a person is seen clearly despite light perception, s/he cannot suddenly disappear even if a wood elf or a skulker. In other words, Hriston does not regard those abilities as establishing an exception to the "seen clearly" requirement. The reasoning seems fairly sound to me.
Anything resulting from a fatally flawed premise like that is highly likely to be wrong. In this case we have errata saying that you can attempt to hide even while being observed, so it goes from highly likely to be wrong, to just plain wrong.
But as far as the Sage Advice is concerned - the presence of observers nearby does not entail that one is being observed. (In this context, "observers" becomes equivalent to "potential observers".) Crawford could, so easily, have written "the elf can hide in those special circumstances even when under observation" but chose not to. That choice is surely deliberate: a deliberate choice to maintain the ambiguity in the rules, and hence to leave [MENTION=6787503]Hriston[/MENTION]'s reading an open one.
And if it just left it at "observers nearby", you'd have an argument. It doesn't, though. It says that you can make the attempt to hide even while someone is staring directly at you. That's direct observation.