[1] https://youtu.be/IzH54FpWAP0&t=530

I had an app rejected, because it had the word "Finder" in its title ("Virtual Meeting Finder"). I had to change the name of the app, and it wasn't too big a deal, because the original name was fairly unimaginative (as it was supposed to be).

But it does sound like the whole app name is in conflict with a registered Apple trademark. It's unlikely to ever be approved.

You could possibly try to register the "INKWELL" trademark for an RSS reader, since that seems quite differentiated from Instagram's claim, but IANAL, so who knows how successful that process would be.

[1]: https://tmsearch.uspto.gov/search/search-results/86733442

[2]: https://tmsearch.uspto.gov/search/search-results/78126699

You lose a trademark if it becomes generic, regardless of how hard you tried to keep it from being so. Obviously if you let a bunch of actual infringements slide you're on the way to becoming generic, but all that matters is whether the trademark IS generic.

But, when lawyers write letters to people saying "you can't say escalator or Zamboni" you can just ignore them. Using a trademark in writing in a way that a trademark owner does not like is not infringement.

Mediocre ones seem to cause the most problems.