I think my issues is more of that Kassyra seems pretty tame relatively in terms of threat level "Pepepains" especially if you gone through her lover route as it is now. And yeah that river comment is in response of that thread despite being different subject but I think it is little too trivial for a separate replies there personally.
You did made a point about the tactics that demons can employ although Marae's in terms of mobility is pretty grounded "Pepepains" so it doesn't felt like a compelling enough example for me to portray how demons vs gods of war in Marae turns out. Also corruption isn't the an aspect exclusively known to the demons given what we've seen the Wraith is capable of (minions).
I mean since human wizards from other universe has access into Mareth, logically that the entities whom are even stronger than supposedly yuman it would makes sense that whatever that is including Wraiths would've arrived before as well and presumably proclaimed "Godhood" on that land similar to the fashion of the Seven in Savarra(once consoom enough "MEGALUL"). Considering Marae's lack of mobility we can safely assume that she is one of the few surviving local deity that probably considered a lesser threat relatively by the demons, which explains how the demons decided to deal with her instead of just wipe her out similar to a fashion of what probably happened to Taoth(Considering the remaining kitsunes in CoC1 had access to their own eldritch pocket dimension that is their den turns out in the exhausted bad end? Can't remember to be exact. And given how enlightened you became once achieved nine-tails I assume that CoC1 kitsunes/Taoth Prime are likely being stronger than CoC2's counterpart at the baseline. I totally would like to have a nod to that though once CoC2 nine-tail is possible, similar to how TiTS done for Foxfire/Frostfire). Also makes the previous Marae example even weaker.
PS: Given that Keros kept Kiyoko's birth accelerating quirk after freeing her genuinely foreshadowed for me that there is going to be a catastrophic event of Taoth's making in the future (aside of convenience for gameplay mechanic which is way more likely to be the actual reason, can't help it, I am sort of into darker stuff)
From writing perspective, obviously that CoC2 with The Seven and The Wraith introduces some power level creeping in comparison to CoC1 which I don't fault them from writing this way, whether it is of some form of oversight or not, unintentionally makes it harder to connect the lore between two games, well not impossible certainly as my post shown. Pardon me of my shitty language and wording, well I made this username four years ago for a reason which granted is probably not the best of all ideas, all things considered.
In terms of power, Marae was the strongest and also the weakest, since being the goddess of Earth, her power is directly linked to the conditions of Mareth!
when it comes to mobility, she was not always stuck on that small island, just after the demons managed to corrupt much of the world, she ended up being stuck in that small lake, which was probably one of Mareth's last pure places, at least until the demons build the factory and start polluting the place!
And in CoC1, we were presented with only 3 of the different gods that abit that world (since it seems that there is practically one god for each sentient species), these gods were Marae herself: goddess of nature, Beast: goddess of predation and Taoth: god of trickery and illusion!
Marae was using all her strength just to resist corruption!
Beast sided with the demons even at the beginning of the war, because she agreed with their vision, and that is why she ended up being sealed inside a pumpkin!
And Taoth had his body destroyed, having to hide his soul in Urta's body and use her and the Champion to be reborn! (and as far as we know, he was the only one of the gods who got to be "killed" by the demons)
we also have to consider that for the 7 to be able to evolve from alpha wraiths to "gods" (losing the ability "unacceptable hunger" and learning the ability, they had to consume an immense amount of souls loaded with emotions, memories, beliefs and values, thing that they could hardly get by feeding only on ironic beasts in an uninhabited world as Mareth was described before the arrival of humans!
Not to mention the fact that when Kass arrives in Savarra, the 7 did not consider her a threat big enough for them to face personally, preferring to send heroes in her name to end the problem. However, when a Wraith emerges from the portal in the ice palace, Lumia itself appears to eliminate the creature! so it can be understood that Demons are at a much lower threat level than Wraiths!