VideoWorks's (1985) sequel, Macromedia director 3 (1993), must have been known to Brendan; they were very popular products., and I believe the FutureSplash animator had a language too. If someone bothered to track down these old products and study them, i am sure you would find elements there. The fantasy that Brendan created a new language from scratch in two weeks is myth. Programming languages exist in an evolution of concepts that inevitably go back to foundational designs, with relatively small amounts added each time. It is extremely rare to see a wholly new language like FORTH was.

Macromedia Director had a programming language called Lingo, which was a close cousin of HyperTalk in HyperCard. And indeed, there are similarities between them and JavaScript/ActionScript, for example: “The Hypercard event model inspired the pattern for adding events to the HTML document.” https://www.computer.org/csdl/magazine/co/2012/02/mco2012020007/13rRUy08MzA