Yeah, that's a lot of code to convert, especially since Java and Python lack some of Swift's nice features. I'd consider looking into Kotlin (built on + completely interoperable with Java), which is really syntactically similar to Swift. If you like Swift, you'll like Kotlin.
On the other hand, if you wanted to start with something a little simpler, you could reuse nearly all of your current code in creating a macOS app. It wouldn't be cross-platform of course, but it would at least give easier access to the editing tools for some users (including Windows users if they want to set up a VM).
I'd love to get involved again but realistcally won't be around for much of this summer, which is a bummer.