Just looked at it, since I never heard of it before. It looks kind of like what I'm trying to achieve, but looking at the specification is very detailed again. It even comes with its own data model for input and output. I don't feel like this should be the focus nor mandatory. It's very Java/Python heavy, which, to be fair, are the two most common languages for these use-cases. But I believe you either have a very static, strong system, as-in shipping a whole BPMN model onto your company and implementing SAP, or you want something light-weight that's easy to use, like e.g. Airflow. I'm more on the light-weight front, but I think systems like Airflow have the problem of being too shut-in into one language. I want my workflows to be quickly defineable (e.g. via Python), but I don't want the Engine to actually run on Python...

I mean, worst case I just gained a lot of experience once I'm done with implementing. I do see a lot of similarities between what's already there and what I'm doing, but also some differences. And it's fun :D