I feel like helium works as well as helix. When I search Helix I don’t get the editor but if I search Helix Editor I will get what I’m looking for.
When I search Helium editor I don’t get any exact matches, but of course SEO is a dark and mystical art so your mileage may vary.
I’m not sure this is a fair comparison, since this is only coming to RCS and not SMS my (completely unsubstantiated) guess would be that this is a message protocol issue.
On the other hand Signal is an encrypted internet messaging service and editing internet messages has been easy for everyone not named twitter for years.