I'm trying to work on a fix for this but once I've converted the Makefile to use QT6 and KF6, the Qt6 cmake config fails with this error while the file it says doesn't exist actually does exist:

-- Could NOT find Qt6StateMachine (missing: Qt6StateMachine_DIR)
CMake Error at core/cmake/rules/RulesQtFramework.cmake:35 (find_package):
  Found package configuration file:

    /usr/local/lib/cmake/Qt6/Qt6Config.cmake

  but it set Qt6_FOUND to FALSE so package "Qt6" is considered to be NOT
  FOUND.  Reason given by package:

  Failed to find required Qt component "StateMachine".

  Expected Config file at
  "/usr/local/lib/cmake/Qt6StateMachine/Qt6StateMachineConfig.cmake" does NOT
  exist