Will Hyle also be able to address external plugins like the Red Giant plugins in After Effects?

Glad to know you like it so far! I currently don't have access to Red Giant Plugins, so I am not able to test it but as long as plugins us standard properties controls (sliders, dropdowns, angles, colors, etc.), Hyle should be able to affect it. Although, every plugin has its own way to behave with After Effects, so every plugin brings its share of complexity and unpredictability. I will try to get my hand on some Red Giant plugins tho to make Hyle able to communicate to it.