I think that people find it difficult to pair innocence with wisdom. 'An innocent' is generally taken to be synonymous with 'a naive child.' Someone who doesn't know any better, someone whose thinking is simplistic, and someone who is easily tricked or misled.
So, a historical figure like
Bonnie Prince Charlie is seen as someone who just didn't understand enough about war and politics to realize that he wasn't prepared to retake Scotland. While he met with some minimum early success...his effort ended badly and he was forced to flee back to the continent.
It's not just that he was young (he was 25)...there's a certain naivete to him. He had some French support, but went forward with his plans even when the ships were lost. He had some Highland support, but not enough to retake the throne of England (which was clearly one of his goals). He had some people with him who understood battles, but he himself did not exactly have a mind for strategy. He was seen as someone who was very idealistic and believed strongly in the divine right of kings, so he just figured it would all work out for him somehow because that is what was right. And so, in the end, he made some disastrous decisions that got a bunch of people killed and ultimately failed in his goal.
We certainly don't want to attach any of that sense of naivete to Lúthien. She's thousands of years old and wise enough. She's no child. And yet...there should be a certain innocence about her. I am reminded of the line 'on Lorien there was no stain' - that land is 'perfect' in a sense, but more importantly...free of the Shadow. That's what Lúthien 'lacks' - she is not hardened by years of battle and betrayal and suffering. She has been able to live her days in peace, and she has no reason to be inherently mistrustful of those she meets. She is, in some ways...untested. That doesn't mean she is easily fooled, but rather that she's not naturally suspicious of everyone she meets. She, like Nienna, will give people a chance.
In her own story, Lúthien is a foil, revealing whether characters fall in the direction of selfless love or possessive lust. Beren and Huan are the former, of course, while Thingol, Daeron (at first), Celegorm, and Morgoth are all examples of the latter. She has been beautiful and the king's daughter her entire life. No doubt she has gotten used to recognizing these reactions. Extremely beautiful (or extremely talented) people get used to admirers...and figure out how to deal with them. Admirers are not the same thing as friends. They...are...hangerson, interested in what they can get out of someone, not having much care for that person as a person. Lots of objectification and attempts at using happen - people want to be associated with the famous person because of what they can get out of it. Songs such as Billy Joel's 'Big Shot' and Led Zeppelin's 'Living Loving Maid' seem to be poking fun at such people...with a lot of acrimony. They don't sound amused.
We don't want Lúthien to be bitter and cynical. She should be someone who has learned to successfully deflect the ill-intentioned gracefully. This is where the 'court manners' will likely come into play. I am not saying we make Lúthien an antebellum Southern lady out of
Gone With the Wind. But she must have a method of easily setting aside anyone who would come panting after her. Perhaps it is as simple as being fleet-footed and easily running away/moving out of the way of anyone who could grab her. But...I think it should be at least a little more than that. She naturally enchants people...and I think that single young men would be particularly susceptible to being instantly enchanted upon meeting her. Can she turn that off? Can she simply let them down gently and have that be the end of it? At any rate, we are going to have her be meeting some people this season, and we can show her approach without making a big deal of it. We might show her deflect Daeron at some point, though they should still be good friends.
It will be a challenge to craft a character who is innocent and open....but not naive. And yes, I know she's fooled by Curufin, but Curufin fools a lot of people. He inherited his father's charisma and ability to sway people. The fact that Lúthien accepts the offered help of Celegorm and Curufin is not proof of her being a foolish child, any more than Finrod inviting them to stay in Nargothrond proves him a poor judge of character...it's just a sign that she's not naturally so untrusting as to be instantly suspicious of them.