After hearing this, yes, she does. 100%. And anyone who disagrees is pretty delusional.
That's not to say she does it on her own (i.e. help with lyrical output), but this song (and many of her others) without these contributions just aren't the same songs.

She's literally adding notes (♪ ♫ ♬ ♭ ♮ ♯) to the song with her layering and texturizing. This is songwriting.

Ouch..those results aren't cute at all. She needs to damage control before hipsters expose this to the general public