There was recently a case on en-wiki where a new editor using this growth tool in good faith was universally agreed to have made a selection of articles equally or more promotional by selecting the "easy" task of copy-editing.
There's a growing consensus at that no, copy-editing is not "easy": good copy-editing requires a native-level proficiency with the target language, and a strong feel for proper encyclopaedic voice in a world where most people consume orders of magnitude more writing that is promotional, forum-esque, or instructional.
Granted there's a substantial subset of editors (myself included, having evidently forgotten my password again) whose first foray into wiki editing was fixing a typo or obvious error from in punctuation, spelling, or grammar. I think articles that are tagged as needing copy-editing for grammar alone may be an easier task, but in the general case it's significantly more difficult than improving sourcing or expanding a very brief stub article.
Anyway I'm not going to propose a bunch of ideas here because it looks like en-wiki are going to have an RFC about it, but I did want to loop in the team here from the very outset, in the hopes that we'll all be able to engage each other and come to an agreement on what best serves everyone's goals, instead of springing the results of an RFC on you once it's already been decided without yall's inputs, which seems like it would lead to frustrations on everyone's part.
No discussion specifically about this growth tool and the any proposed modifications that will improve everyone's experience has yet been opened at the time of this edit, so please consider this post as generating awareness. I'll follow up with a link to any RFC once one exists. Thanks for your time.