Proposing an improved translation is absolutely the right approach. Adding a brief note explaining why your version is preferable also helps a great deal. Tt gives reviewers the necessary context and makes the evaluation much easier.
At the moment, suggestions on strings that have already been approved often don’t get revisited. This is particularly true for reviews handled by the translation agency, where approved strings are typically treated as final.
To improve this, we plan to extend our internal tooling with a button that removes approvals from strings that have received new suggestions. It won’t run automatically; instead, we’ll use it intentionally before handing work over to the agency so those strings are clearly returned to the review queue.
The aim is to have this in place within the next one or two releases. I’m assigning this topic to myself to ensure it doesn’t fall off the radar.