Firstly, I think the whole Akina livestream subplot was incredibly redundant. Especially once they revealed that Mei and Hibiki's family had a connection to the jukai curse and the box for at least 13 years, I just felt like Akina and her whole deal had no place in the movie. It would've been fine without it since the box and the jukai curse are interesting and feel unique. They probably only added Akina cuz she was in howling village and ox-head village so they needed to add her in for the last movie of the trilogy.
Next, It's a shame they didn't explain why the box ended up in the house the couple moved into, and just used it as an excuse to kill a bunch of Mei's friend group. Compared to the other two movies, this one holds last place (although I wouldn't say it's a terrible movie).
The english name also sucks incredibly hard. Sure, it's a reference to Aokigahara forest, but just omitting the word "suicide" would make it fit the movie better in my opinion, since the topic of suicide isn't really explored in it and just focuses on the curse making people do things against their will. Also why the hell did Mei and Hibiki's mother sacrifice herself to save their kids when the stupid box will try to take them 13 years later anyway? Makes her death feel useless.