Our approach with flowcharts is, currently, as a data structure only.
I have 2 cents in that regard. I've been more and more going into javascript and I'd say handling any kind of data structure, being array or json is so much easier and flexible in javascript.
One big thing that Construct does very well are the visual editors. 2D/3D array editor, awesome. Flowchart editor, also awesome. Json, well that's just a text editor, but also perfectly fine. But manipulating these data structures in the context of the eventsheet... I dunno, either it just doesn't work for me or it actually is very cumbersome. Flowcharts are shaping up to be easily the most cumbersome data structure to handle in events. Although I have yet to properly test the usability since it's currently crashing a bit too much to test this.
I don't exactly have a solution here, I just feel like that eventsheets are not that well suited for that type of data-driven work.