Yeah, but Jellal was stronger than in Alvarez, but God Serena was weaker. It is established in the manga that the Magic of the dead people is lower and Serena had a pretty obvious weak point, being his wound he got from Acno.
Don't get me wrong - Jellal is a beast and one of the strongest characters in the manga (he always was), but this Hiro's statement about Spriggans' power doesn't really prove Laxus v Jellal situation as they respective fights were completly different.
It's also worth mentioning that this Spriggans rank is made for the upcoming game. We don't know yet if the game is 100% strict to the manga (well, to the anime, game's official site states that the game is based on anime not the manga somehow

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