Without getting too preachy about it (hopefully), I have to say this once, at least briefly --- Age is just a number. It doesn't matter how old you are; it's about what resonates with you personally. And if getting older means not being able to embrace your own unique essential nature, then well... I wouldn't really call that "growing up." (I say this in general about the matter; I'm not implying that you don't necessarily know this)
But anyway, as far as a deck being Teen oriented - the Oracle of Shadows and Light, for example, is written directed toward a teen audience, but with tweaking in your mind as you read, I find it can translate perfectly well for any age. (For example, when it mentions school, are we not all in school? the school of life? we never stop learning). I didn't find it difficult to relate to is what I'm saying and a lot of these decks mentioned seem to be very popular with so many people of different ages... The authors of these decks are not teenagers, for example, and I'm sure they resonate with their creations and they intend the same for whoever is drawn to them.
I don't own the Enchanted Oracle, but I've looked at it and it does seem like a beautiful deck! If you're drawn to it, then please don't let some concept of age act as a barrier to something that may delight your timeless heart... I wish I had actual experience with this deck so that I could say more about it specifically. But I actually watched her video about it too, and since she mentioned that this deck is a bit darker than some other faery decks, that is enough for me to assume that this deck should probably work for those who are older... I think that's one thing that we perhaps mean about a deck being too "young" - does it embrace the depth and complexities of life, does it honor both the darkness and the light, etc.
You have to trust your own gut feeling. Sometimes a deck doesn't resonate and that's totally fine and quite usual, but just double check your feelings to see if perhaps there's something else about the deck that doesn't resonate with you that has less to do with age and more with style, for example.