Mildly warm take time again.
Ditch the echo labeling. At the end of the day, they're still clone characters. It may have quelled the complaints a bit for one game but people who don't like clones aren't going to stop disliking them. Plus, there are still non-echo clones anyway.
More to the point, it ultimately doesn't mean much within the game itself, but I feel like it's had a negative impact on character discussion.
Sure, the "echo" branding warmed some people up to the idea because it's another box they can try to fill, but it's inadvertently made it more difficult to discuss some characters who are now more readily dismissed as only being echo material and nothing more. And with echoes by nature being more restrictive than "traditional" clones, half the time the suggestions wind up failing to meet the criteria anyway.
More often than not, when people ask for echoes, they then go on to describe a clone and not an echo.