Been there, done that. Didn't even get a print out of the translated chapter, nor a hard copy of the edited volume.
Make sure the article is at least of some interest to you personally, otherwise the whole process quickly becomes taxing.
The assumption is also that you will translate into a language that is your mother language, or that will be even harder, and actually you would be badly advised to even consider completing the task.
Translating does not improve an academic CV because translating an article is either a skill people assume you have to be able to carry your usual research, or translations are given to language professionals who can value the experience on their CV.
Unless you're able to bargain some sort of deal that is of interest to you with the people who ask for the translation, or the author of the article to translate, it will only be a "service", for glory.