I think the ARC-AGI tasks was manually drawn with an early version of fchollet's editor.
Recently Michael Hodel has reverse engineered 400 of the tasks, so more tasks can be generated. Interestingly it can generate python programs that solves the tasks too.
No, his re-arc code does not enable generating more tasks, it merely allows to generate more examples for the already existing training tasks. Also, it can't generate task-solving programs either, it's author merely also provided a solution program for each generator program to verify the validity of the generated examples.