Passing Parameters in functions from AS3 to JS FL (Adobe Animate)

Hi there, I'm currently writing a tool in AS3 and JSL to work in Adobe Animate. I'm calling functions in JSFL from AS3 via

Code:

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MMExecute("fl.runScript(fl.configURI + 'WindowSWF/import.jsfl','ImportFile');");

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which works, but ideally, I'd also love to be able to pass parameters.

I've tried the folowing approaches:
1. ExternalInterface.call - but as I'm running the app in in Flash IDE, there is no environment to communicate with.
2. I've considered writing a JSON cache file to dump out variables, that I could then read via JSFL. However, actionscript won't allow the saving of a file without express user permissing (a dialogue which I don't want) and I've also tried SOL objects, but JSFL can't read these.

Is there any other approach I could try?
Many Thanks
Ant