You're never going to get me say anything is screen accurate. There's just too many variables. Especially on ESB when we know parts were swapped around, and the prop changed significantly throughout the movie, if it wasn't in fact multiple props.
Everyone is obsessed with getting the Wampa Cave stamping to match, and yet no one wants to shave down half the grips, keep the beer tab, put an early Folmer button on and short blade on it. The Wampa cave was a short-blade stunt, not a belt hanger. But yes, it was an Early Folmer.
The Dagobah WAS a belthanger-- but was also missing a button. And we know it's a Folmer Patent.
Point being, there's no one true ESB version of the prop because it changes so frequently.
So I wouldn't say that all Graflexes used on ESB are Early Folmer or Folmer patent... we do not know that. But I would say that we know one of each was used. Just like I wouldn't say Disney has made the worst Star Wars movies... but I would say the worst Star Wars movies have been made by Disney. (Because I think Rogue One is as good as the OT, but TROS was a complete disaster.. .for example).
I would also say that Inc. Graflexes are so ubiquitous, I'd be shocked if they didn't have some in that box as well.
You want definitive answers where there are none. It kills me too.