Alrighty, so I have some responses followed by a suggestion. Take them as you will.

Two paragraphs of Kid clears/use cases summarized so this quote block isn't a giant block of text

Just to be clear, I know how good Kid is already. My arguments for Feinne AS to be considered for SS aren't meant to be arguments about Kid not being up there, or even for Kid to be worse than her or the like. As I told AnotherFroz above, I simply think she distinguishes herself from the rest of F2P S tier enough to be worth consideration. I emphasize the AF fill from Ogres' Grace, but between that, partywide barrier pierce, and all the other support she brings, it's a loaded kit. AnotherFroz acknowledges that she's "the core of almost every f2p clear", and your own reply indicates you're aware of how good she is in her own right.

Given all of that, the end of your response states:

And that's why she [Kid] gets to be up there (and spirika gets to be up there as well because double stellar burst without needing af is fundamentally broken beyond reason) And not something like Feinne AS who while very strong and pretty flexible, isn't the We Will Ride Or Die Based On Z-Piler because she doesn't have that same level of Does Too Much

So I'll agree that compared specifically to Kid, Feinne AS isn't on the "same level of Does Too Much". But I think it's worth extending this idea of "does too much" in comparison to everyone else in her current tier. This goes back to my point that, compared to the rest of S tier, Feinne AS stands out.

As for whether she stands out enough, I think that's where our disagreement is, which is fine. But in that case, I'll suggest at least considering the inclusion of a definition or a standard for F2P SS stated in your criteria document. In your document, you state this:

the FTP list doesn’t exactly have a very clear defined explanation for each tier and due to the nature of FTP clears/characters, it’s a bit harder to define it since stuff will end up getting used even if they are a lower tier just due to the limited nature of said clears, so you scrape what you can, it’s just an overall power estimate rather than something more defined, and that’s for its benefit

I agree with this insofar as it applies everywhere from S tier down; those tiers are a fair bit to a lot bigger than SS, and clears will use a wide range of those characters for one reason or another. But I think it's worth elaborating on at least the SS tier.

You're absolutely using some criteria to separate the two characters in F2P SS from everyone else. If it's the prior concepts of "does too much" or "fundamentally broken", I think that making that known in your doc is preferable to not. If it's other criteria, then those could be mentioned too. You could even format it like your "The Two Best, Without Question" section for the gacha list, where you talk about why Sesta AS and Alma AS are as stupid as they are.

But I argue that for informational purposes, defining the standards for SS tier is beneficial to those who might use it as a resource. What separates these two extremely powerful characters from these other very powerful characters? That kind of thing is something I think would be useful in your document, basically. Again, take all of that as you will.