BushelScript is an open-source AppleScript alternative:
BushelScript is open-source and community-driven, meaning it can undergo necessary changes and gain useful features rather than remain stagnant as a side project on life support.
The real tragedy of AppleScript is not its becoming obsolete or irrelevant; tons of Apple-supported macOS apps still have healthy scripting interfaces. No, the tragedy is that the language through which such functionality is presented, with all its quirks and weak points and even utter failures, is extremely unlikely to receive any badly needed improvements in the future, if any changes at all. It is stuck in maintenance (read: bugfix and security hole-filling) mode and will be for years to come if we, the users, don’t replace it with something better whose fate we can control.