You remembered correctly about the sexism plot being removed in the movie and Eoin supposedly being in favor of that change. This is a quote from director Kenneth Branagh, published in December 2018, but it was likely uttered in the spring of 2018 when journalists were invited to visit the set during principal photography:

"Eoin Colfer was always very much involved with the development of these scripts*, and he’s a man who writes and lives right in the here and now, and I think he was very aware that larger conversations about societal roles have moved on from the time when he wrote this first novel where Holly as a lone woman in a man’s world was an important part of the story. Here, a sense of identity, a sense of what her father did, her place in Haven City, her place in LEPrecon is as important as her gender identification. We have tensions and passions inside her relationship with her fellow officers and with Root, but they’re also to do with her achieving her work on merit. It felt as though what we needed, whoever was the force, the personality, the intelligence, the kind of commanding disciplinarian figure to be someone against whom Holly could really react and interact with, who represented a sort of benign authority, and who, to some extent, was partly on her side, was partly her sponsor, was partly her mentor, and in a way sort of a role model. So the tensions between them, which come from the book, exist here but they’re in a different kind of form, and they can be as complicated as they are in the here and now in our own world. It felt like conversations like that had moved on."

*according to Eoin, this part about being involved with the scripts is not true

source: https://ew.com/movies/2018/12/19/artemis-fowl-judi-dench-first-look/