Your arguments are not good and do not match the reality of the manga. In fact, you are making several conjectures that place Minerva and Kagura at the power level of high power level characters (Jellal, Erza and Laxus), as a way of establishing a power parameter above that shown by Lucy.
This happens because these two characters don't have significant achievements in the manga, so you want to push this narrative to mask that.
First, you are distorting this scene where Erza is caught off guard by only presenting the manga page that you think is convenient to show. Initially, Erza used into an armor with great defensive power, but Luso Signario undid her armor, leaving Erza perplexed. And soon after that, Luso tried to bury Erza with a huge plush, but Erza managed to destroy the plush from the inside, but she was unable to do so react to the next plushie because the attack was out of your field of vision.
To illustrate, this happened twice in this fight:
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Erza dodges the first attack, but is caught off guard by Luso's other attack.
Furthermore, after Erza uses Reequip, she with the Tenri armor manages to destroy all the plushies that came from different angles.
And feel free to bring other situations from the manga, it won't change anything in the context of these scenes of the fight between Erza vs Sisters Signario, since anyone is capable of interpreting these pages of the manga.
And again, Lucy wasn't outmatched by Kiria due to lack of reaction or speed. What happened was that Kiria destroyed Cancer's scissors and cut the Lion Maiden, leaving Lucy without many options. She opted for Aries' Star Dress, which has defensive spells, and was thinking about how to counter Kiria. But she found himself without options.
Before Kira destroyed Cancer's blades, Lucy managed to react and overcome Kiria in blade combat. But after Cancer's blades were destroyed, Lucy no longer had the offensive potential to exchange blows against Kiria at short range. Would she protect herself with her hands? Obviously not. That's why she wore the Aries Star Dress.
Kiria surpassed Lucy at short range because Lucy was left unarmed, with just her bare hands (Hiro even emphasized Lucy trying to use the celestial whip to continue in close-range combat, but Kiria cut him off. Proving you wrong).
The funniest part of your post is that you assume that Minerva and Kagura would do better than Lucy. If it had been either of them in Lucy's place, they would be dead. Kiria would destroy Archenemy, leaving Kagura completely unarmed and defenseless (Kiria destroyed Erza's Benizakura). After that, Kagura would be killed, as she doesn't have any spells on Gottfried's level or useful magic to keep fighting.
Regarding Minerva, it would be even easier for Kiria, as she is able to cut through magic without difficulty. Then Minerva would have no way to fight, and even if she did, her explosions are useless.
Kiria would have no difficulty against Minerva and Kagura. They are less versatile than Lucy and weaker too.
And if you think that reacting to HUMAN DIMARIA and fighting Erza from Sun Village are good feats for the quest parameters, you are extremely mistaken.
An important point, the Spriggans in their history version are weaker than the original version. And Mineva WAS IN DOUBT IN THE MANGA ABOUT BEING ABLE TO DEFEAT WHAL, as Makarov used Fairy Law to destroy Zeref's army.
Good luck inventing feats for Minerva, she needs it.
And please, are you using the fact that Minerva participated in a battle against Luso Signario where only she actually fought the opponent, to claim that she is gravitating towards Erza and Jellal's power level? If so, Wendy is on par with Erza for helping against Irene. Gajeel-level Levy for helping against Bradman. Among countless other situations. This argument was very low on.
This just shows how you don't have good arguments to support a level of power that these characters don't have.
You showed the Jellal scene wrongly, as he is portrayed as insanely powerful. Being unaffected by Kiria is not relevant to this discussion.
Furthermore, Minerva does not have any relevant achievements in the manga. Her explosions are a joke and she has nothing else that can be used in combat. And Kagura... this character was made a joke in Alvarez, and is "dead" in the quest (she barely appears).
Minerva and Kagura were only not surpassed by Juvia because Mashima is too worried about Gruvia's fanservice. If it weren't for that...