It's not a pedantic distinction given how much the term has been overloaded to refer to dissimilar concepts.
For something to be called FRP, they at least need both continuous and discrete abstractions; the simplest description of FRP involves re-evaluation A + B over time, which is not meaningful in Rx or Elm, really.
In Elm behaviors and events are the same thing. Usually operations like filter and fold are only on events, and applicative functor and monadic operations are only on behaviors, but in Elm one type support filter and fold and the applicative functor operations, and monadic bind is not supported at all. I don't think that's good design, but it does mean that Elm has the functionality of both events and behaviors.