I started a large solo project in late 2019 using Swift. I have no trouble compiling and linking the project today. I have been adding Swift code to an old Objective-C project without issues. There was an open source objc project I tried to modify recently, and was told that a feature was so deprecated that using it was no longer an option, forcing me to consider rewriting a large swatch of objc code; it just got so convoluted that I bailed.
Early Swift adapters got the arrows in the back. I was not an early adapter.
The criteria for an effective release tends to be more prickly when deployed to a million users and, to certain companies, a million users is a tiny audience. Know your audience.
I'm thinking that a demo of the app to a couple devs you know who have stuff in the app store might help gain some insight. They know the process and may have experience in what to look for.
Early Swift adapters got the arrows in the back. I was not an early adapter.