I've worked through a major publisher to contribute applied portions to several textbooks, and am listed in the acknowledgements sections. These were not one-day content reviews and singular practitioner projects, but ongoing contributions spanning over a year. I currently have the books cited under the work experience section in my industry resume, via employment through the publisher while citing the primary authors and disambiguating my role in the bullets. However, as I apply for a second graduate degree, I am wondering if the books should be moved up to the publications section (still citing the main authors and not myself, of course).
In case this is relevant, the publications section currently has four direct authorship items, so isn't empty. Still, they're nothing special, and I'm concerned about down-playing the textbook work in my apps.
Similar questions have been asked about generic contributions in papers, minimal contributions, and paper authorship as an anonymous team, but I am unsure if this advice applies to textbook-scale work.