It's not a matter of Heroes not being canon, but of Heroes being another continuity entirely; the premise is that the Dragon Ball universe is an in-universe video-game played by kids. It has no direct ties to anything else (besides using the characters, obviously) and things happen differently in its presented events than they do in regular Dragon Ball, from other people being involved to smaller details changing like Black not being transformed when Fusion Zamasu is created or power scaling between forms being different.
Simply put, Heroes has its own vague version of events that have occurred. They are not the same as what occurred in any other canon, and therefore feats are non-transferable.
Further muddling it is that Heroes itself is a bunch of different continuities between its manga, anime and game trailer forms. Cumber's fights go differently in all of them.