Effects on their own are a very active area of research and I would laugh behind a PL researchers back if they claimed it was a solved issue. Between Monads, call-by-push-value, and algebraic effects there is really no clear "how do people actually use this" answer.
But that's not the job of a PL researcher anyway, or a random software engineer for that matter. Sorry to say, the software engineer knows next to nothing about "the right way" to design language features that people want to use or enjoy using. If anything this should be an HCI person with a penchant for PL or vice versa.