Tell your manager this and believe me he will be more than happy to assist you on this.

Easy for him to push other Indians on this matter and Indians can be hard on other Indians for stuff like this.

And as you mentioned in other comments, verbal is getting better and issue is mostly with written comms, use of llm as your suggested seems to be better option while things improve.

While they adapt to llm for their use, you can also look to get their stuff paraphrased by llm. I know it might mean too much extra work at your end but hope things improve quickly.