"He brushes his teeth right after finishing meals."

Translation: 他吃完饭会马上刷牙。

[hebozhe]

Is "會" required here? It seems like you'd need an auxiliary "will" or "would" to make that more precise.

[Blue-Core]

“会” is required here because the sentence contains the meaning that "brush teeth after dinner" is a habit for him and that he will do it everyday. Adding "会" makes the sentence sound more naturally, in other words, makes more sense.

[andrewkozak]

You're inferring that the sentence in English is discussing the future behavior of the subject and not just a statement of fact

[MrC314159]

Is there anything wrong with saying
”吃完饭以后，他马上会刷牙” ？
The English says “after finishing meals”. Surely with just “吃完饭” on its own it only means “finishing meals” so ”以后” is needed to convey “after finishing meals”?

[andrewkozak]

"会" implies that this is a statement about future events and not a discussion of a past/present habit. As such, there should be a corresponding "will" or even a "will always" in the English