Can you recommend a storebought cracker for this recipe? We have a Whole Foods and Trader Joe’s nearby. Thank you!

This is a lovely recipe, and the combination of sharp (radish) and aromatic/slightly towards the sweet (vanilla) would go well with a dark and fruity cracker.
There is a brand of small-batch very crispy cracker called Lesley Stowe Raincoast Crisps (from BC, which I discovered when working in Alberta about 10 years ago). Flavors like fig and olive, or cranberry hazelnut.
They are now sold in the US at Whole Foods, Ralph's, Publix, other stores. Although I didn't see Trader Joe's on a quick check of the website, I've started seeing no-name or store brand versions, so maybe they have something similar.
http://www.lesleystowe.com/product-line/raincoast-crisps/

The recipe recommends a very plain cracker, i would think Carr’s water crackers or their water crackers with black pepper would work well here. (Whole foods or other groceries, trader joe doesn’t have an equivalent)