@Pluton9
Regarding level 4
That tweet never indicates that it refers only to characters who have debuted; when Omori tweeted that Alfia and Zard were the most powerful characters in the franchise, he clarified that he was referring only to those who had debuted, which shows that Omori does make those kinds of clarifications when they are pertinent, so you have no solid basis to defend your point.
But leaving that aside and focusing on the facts, your logic has another problem, according to your reasoning Anya should be listed as number 1 on the list, because she is level 4, from the Freya family and had already debuted, but she was not even listed and in the Ryuu episode it was quite clear that Ryuu is stronger than the other 3 waitresses...
As for Aisha, during the war game she proved her supremacy, she was the only level 4 on the south flank and no second class adventurer of Freya could beat her, they had to send the Bringar to defeat her and not even they could beat her when they were equal in level.
It's not about that tweet anymore, it's about Aisha factually proved that she is the strongest level 4 and she is not from the Freya family.
Regarding Level 6
In SO10 when Finn, Gareth and Riveria fight together against Revis, it is mentioned that it had been years since they fought together. They can fight as a team and that doesn't mean that they don't have individual duels; it's like a medieval battle between Vikings and Britons, yes, there are 2 teams but in the heat of battle there are individual duels where each one fights against the opponent in front of them.
Finn mentions to Lili that he had fought against them many times and the members of the Loki family mention that before Revis they had never seen Finn lose, which implies that he never lost against them; it doesn't mean much since Omori never defines the fights between relevant members but anyway, it shows that he faced others who supposedly should be better than him and it wasn't like that.
You're right that the Loki trio leveled up because they got involved with Enyo and Freya not until the end, but for this purpose what does that matter? They trained more and improved more leaving their rivals behind, progress is the reward of effort. As for that gap closing soon, I don't see how, the Freya family doesn't explore the dungeon so they have no way to progress, whereas the Loki family does, so the logical consequence is that the gap gets bigger and bigger with each expedition, instead of closing.
As for the efficiency between the methods, obviously the Freya family hasn't had any fatalities, if they don't go to the dungeon who could kill them? But in the last 7 years the Loki family has brought 5 adventurers to be first class, whereas Freya has brought how many? ..........none, they have exactly the same 8 first class adventurers they had since the big Feud, no need to ask which one has the best method to progress.
Regarding MS17's fights, yes, Bete used beastization, what's wrong with that? It's his skill, didn't Allen use his skills to fight? Bete would make up for his smaller status with his skill, but if Freya's executives are so superior why didn't Bete end up in intensive care? We didn't see any post-battle injuries.
We only know that Hogni fought Tiona, we have no way of knowing what else happened so let's not talk about it.
By mentioning the youngsters I wanted to emphasize that the fact that they didn't have any injuries puts into doubt that a Freya member would literally defeat anyone with their same level.
In short, he can say in 2, 3 or nth novels that Freya members are stronger than any other but when it comes to the Loki family, the prooves are missing, where is the evidence that shows they would beat them? Also Raul and company intercepted Freya's members along with Bete and Gareth, were they defeated?
As a final reflection, Hedin told Finn that thanks to Ottar they were guaranteed victory even if the Loki family participated, curious precision to emphasize that it is thanks to having someone with a higher level that they can win if it were true that each of them is stronger than their counterpart of their same level because in that case why would Ottar be essential? Don't you think?