Adapting Matilda the musical for a movie will face a similar problem that the book had when adapted for the 96 movie; IT DOESN'T FOLLOW A TRADITIONAL PLOT. There is a through line of following the life of Matilda when she starts school and her interactions with Miss Honey and Miss Trunchbull, but its more a series vignettes instead of building toward a climax. In the musical Matilida's powers aren't introduced until halfway through the 2nd act, which yes aligns with the book, but it wouldn't work on screen. Instead the first 2 thirds of the musical and book focus on the everyday goings on in Matilda's life and how horrible it is.
The 96 adaption much to the chagrin of the Dahl estate introduces Matilda's powers in the first 3rd of the movie and her use of them grows as the terrors thrust upon her and her fellow students by Miss Trunchbull escalates. In the movie it is Matilda who saves the girl who is thrown by Miss Trunchbull with her powers, while in the musical and book she is just a bystander. Add to that of the score is made up of mostly character songs, which are usually the first to go in a film adaption. Very little of the score advances the plot, but instead it mostly comments on it. The only 3 truly plot advancing songs are Naughty, Bruce, and Revolting Children. If it were to be adapted Minchin, Kelly, and whoever they hire as a screen writer will truly have to tear apart the show and rebuild it from the ground up for a film adaption.