2015 rMB 12” w/ a Return key that wasn’t working very well. In early March of this year (2019), the guy at the store said they might need to replace the battery too, because of its relationship to the top case. He sent it away and said to expect it in several days or a week or so, but I got it back a couple days later. The battery wasn’t replaced, but the top case looked brand new, and the keyboard worked well.
The document that came with the fixed MacBook noted the battery condition as “normal,” same as the battery health noted on-screen. Not sure if this had anything to do with their not replacing the battery. I wasn’t expecting a new battery though, so it wasn’t a big deal.