Sorry, but you are all wrong. It’s not RNG, and not a grapich failure. Einia gets stunned but she can attack after that. The thing is that a creature skips their next attack, not their next turn. I explain it why. Turn by turn.
First attacker: Enia because she is faster.
Second attacker: Iguanodon uses Superiotity strike which slows Einia down.
First attacker: Iguanodon uses Greater stunning impact and stun Einia
Second attacker: Einia is stunned. Can’t attack.
First attacker: Einia can attack this turn because she gets her speed back.
Second attacker is Iguanodon now
So basically Einia attacks after she gets stunned, because this turn she would go second but next turn she goes first. If Einia wouldn’t get stunned she would attack twice. Because this turn she is second and next turn she is first.
And this is why I think it’s a nerf for these types of creature (Ouranosaurus is the same). I don’t like that.