Same feeling with the trailer. I just can’t see it working, LOTR and animation could work so well, but not with generic anime style. They needed to flesh their own style for this to work well, just like Fortiche did with Arcane.
I’m not big on anime at all, so I am not drawing on a broad range of experience here, but I can think of at least one that I think really matches the feel that you’d want for an LotR adaption: Sword of the Stranger
I’m gonna guess you don’t mean the Russian adaptation from 1991: https://m.imdb.com/title/tt12121178/
And you mean this one from 1977: https://m.imdb.com/title/tt0077687/
I haven’t watched it but based on the screenshots, while an outdated style I’d rather say I like the character design. A bit too cartoonish and childish but that kinda belongs in the realm of the Hobbit, so to me it fits quite well.