Alright. Please let me know when you're done with that.
Eh. There are a couple of backgrounds and classes that give proficiency in Insight, along others, in the Player's Guide already. I think it should be something that plays with the siren-esque aspects of their myths instead. I believe tieflings have an ability that lets 'em cast a cantrip at first level, a 2nd level spell at third level, and another at fifth level. They can only cast these spells once per day and must take a long rest in order to use them again. They can cast the cantrip as much as they like, there's no limit to it's use. Maybe you should use that.
I think this race knows too many languages. The ones in the book have only two, their native tongue and common (that is, if you don't include their subraces).