Apparently RapiD also truncates changeset comments instead of warning you about the character limit :(

Added addresses to the duplexes on Algonquin and Amelia Drives in Cedar Falls, IA. Each building shares a single house number, and each unit has a unit number. This is really unusual for Cedar Falls (usually each unit in a duplex has its own house number), so I confirmed with a survey before adding the data from ESRI. Since RapiD has a 50-item limit, adding them all will take multiple changesets.