This discussion about swimwear terminology is more interesting than anything Anna has done all month. I'll throw my two cents in, as another American. I always said "bathing suit" growing up, and now I say that or "swimsuit." Never heard of "swimming costume" (to me, a costume is for when you're trying to impersonate something else), "cozzies", or "togs".
Re: Allison Roman, she's like the poster girl for 20- or 30-something gals who live in cities on the coasts and who identify with Glossier, Bustle, "Girls", and the like. Your cool bestie, in other words. I like her recipes, but her manner of speech bugs me a little. It's a little too millennial valley girl, therefore suitable for Anna to copycat.