Not necessarily; there are a few SNES games in the Switch Online library that weren’t localised and hence remain untranslated from Japanese, namely Super Puyo Puyo 2, Panel de Pon, Mario’s Super Picross, and Kirby’s Star Stacker. Though all of those games are puzzle games, which don’t necessarily need language to be enjoyed, whereas an RPG like Mother 3 would likely be much less enjoyable without understanding the dialogue, battle UI and so on.
Yesterday, the developers of Garry’s Mod, the 2006 Source engine sandbox game, announced on Steam that due to a takedown request from Nintendo, they were removing all the Steam Workshop (i.e; user-generated) content that used Nintendo’s IP. Some originally believed that this was a troll of some sort posing as Nintendo, but this screenshot tweet from Garry Newman, the titular developer of Garry’s Mod, indicates that he’s certain the takedown request is legitimate, and the probably-still-ongoing removal of Nintendo content on the workshop will continue.