I play vanilla game and I currently play teen girl who has socially awkward and loner traits. And she doesn’t fail all social interactions. Most fails happen when tense moodlet takes over or when she is trying to tell cool joke (but in playful moodlet she also get positive reactions). Normal stuff like tell story, ask about day or discuss interest works normally unless she feels bad.
Those sims should work on their charisma skills more, but what you describe is excessive and I don’t think it’s normal. I played only 3 days and my sim already has one friend. With this trait it’s important to check their emotions, if they feel bad they will most likely fail.
Edit: I just realized you are talking about sims acting LIKE they have this trait, sorry, my bad.
As for relatable trait I always get some two green pluses when talking to fellow teen so I guess it works as it should.