Glad you loved the concept!
Unfortunately I've been rather busy the last couple of years and haven't had the capacity to work on Shortcat, and coupled with not being amazing at Obj-C/Swift/Cocoa (my major contributions are FuzzyAutocomplete and the initial POC for Semantic History in iTerm2), being frustrated with building UIs on Mac (mostly build web stuff). There's also the problem that Accessibility APIs aren't well-documented and isn't commonly used, and applications not implementing Accessibility correctly (and potentially causing crashes in Shortcat, or making the target application hang), which was super tough to deal with as a solo dev.
I did have a crack at bringing the Swift-based prototype up to date with Swift 5 on the weekend, and am investigating the feasibility of using SwiftUI which would help me on the UI front! Ideally I'd find another dev to work on Shortcat (rev-share or otherwise), and consider a more sustainable pricing model.
I think tools that depend on Accessibility APIs that are used by people who don't normally depend on Accessibility APIs can force developers to improve their AX implementation so people who do depend on good Accessibility to use applications can benefit.
It makes me happy to hear that it was good enough for you to buy another copy!
How did you discover Shortcat in the first place?