Yueh isn’t a mentat and his betrayal is unrelated to mentats. He’s suk, but even this is not integral in understanding that he was a trusted part of House Atreides and then betrayed them. The rest really isn’t needed to further the plot.

Movie adaptations will never be able to be as detailed as books. People that first read a book and then watch the movie will almost always notice there are things that are missing, and if those missing things are something the watcher was really attached to, they will be disappointed. But for people who haven’t read the book, as long as the missing things don’t create large plot holes or confusion, it’s fine. I think Dune does a fantastic job of striking the balance of detail while still telling a cohesive and fascinating story. Stuff like mentats and suk doctors are really fascinating and it’s unfortunate that movies don’t have the time available to expand on them, but the movie is able to stand alone without it.