Is copyediting good for an academic career? I have recently been involved in managing a special issue in a scientific journal. The chief-editor was somehow appreciative of my work and now wants me to join the journal's board as a copyeditor. I am puzzled by this request since I have no example of an academic being involved in such a task. Usually, being an editor (see Why become a journal editor?) involves more content evaluation.

Would my academic career take advantage of such a duty?
The only benefit you'll get as a copyeditor is clear: money (assuming he offered to pay you).

The downsides are numerous: it takes a lot of time, it will not be considered a plus to your CV (it's a technical job, not a scientific one)… none of the benefits from being a journal editor apply to a copyeditor.

Also, I don't know exactly what you did when you say “I have recently been involved in managing a special issue”, but if you were guest editor, offering you a copyeditor job is clearly not showing appreciation for your job as a scientist.