If you've ever really listened to Colbie Caillat lyrics, then you know
they are simple, yet extremely relatable.
the implication being that they are relevant for me, the person making the comment. La letra es sencilla pero súper relevante.
It's not an exact equivalent but I think it's functionally equivalent.
One of the reasons for her success is that the characters in her books are so relatable.
As to whether this is a false friend -- maybe it used to be, and maybe it still is among purists -- but here's an example from a newspaper in Spain of it being used with that meaning:
La canción de Nirvana, Smells Like Teen Spirit, fue elegida como el tema más relevante e icónico de la historia tras un estudio realizado por Universidad de Goldsmiths.
Again, when you look at the two words side by side, you wouldn't be tempted to put an equals sign -- but I think the functions fit well with each other. Los personajes en sus libros son simpáticos. Meaning, I, the person making the comment, feel comfortable and drawn to the characters. I'm looking for a natural way to express the feeling of each sentence, in a natural way, as I would do when talking with a friend.