Re: the issue with writing multiple construction sets into one JSON file, I recommend that you use the “HB Dump Objects” component for this purpose. If you connect up a list of construction sets to the _hb_objs of this component, it will automatically format them correctly so that the multiple sets get written into one file. All of honeybee expects such “multiple objects” JSON files to be written as a dictionary (curly brackets) with the identifiers of the objects as the dictionary keys and the definitions of the objects themselves as the values (similar to what you see here in the honeybee-standards repo). But the Dump Objects component takes care of all this formatting for you.
Also note that you can use the indent_ input of this component to make the resulting JSONs more readable in a text editor.
