I like the idea of non-linear crown distribution, especially the version suggested by @kalkulus. And tbh I think changing that one aspect could improve player experience a lot and encourage guilds to move to higher tiers. I don't think there is enough dev time available to make huge changes, so it would be nice to get the most out of this one change.
The only drawback I can see is that ... it would be difficult to explain to average player how that "hyperbolic tangent" distribution works (but hey, it's not easy to explain current way either!).

Also I am not a fan of relegation system, the problem I can see that e.g. guild who has exactly X players to fill X frays will be forced to fill X + n frays and different levels of them. Sometimes guild is just not ready to advance even though that guild wins brawls in current tier. But maybe guilds would just adapt.

Great post overall, I hope we can find some consensus. I will definitely support the proposal.