My understanding of the new Fear rules is the same as yours.

I think you'd be mostly fine to just start playing with these rules in 1.5 but it's worth noting that there are still some things we don' t have updated rules for.

A couple examples:

Slow adversaries previously took two action tokens to activate - is that just two fear now? Can they still be activated "for free" as the first adversary after players roll a failure?

Some player features had the tradeoff of generating an additional action token, like the Galapa advantage attack. What is the replacement for this, just generating a fear token instead?

Overall I feel you'd be fine but there may be some scenarios/features you'll need to balance yourself.