Edeldross actually does open up a way to generate findross with the tools you have now, though the mechanism is somewhat obscure...
I love puzzles.
So, what is findross? Well, we know it possesses the superlative quality of making things be as they should.
What is Edeldross? "This precursor component of findross embodies redemption, perfection, restoration and the renewal of cycles. It is the liminal gloss between real and ideal, whereby the purposeless matter of the corporeal world becomes the refined substrate of supernal augmentation.
One way to produce findross would be to create Edeldross, then use incident Nullification to nullify every concept but perfection and restoration. The resulting substance would restore things towards perfection, which sounds a lot like Findross.
[ ] Incident Nullification - Gisena is able to nullify specific phenomena or concepts on which she has practiced extensively; the more abstract and influential the target, the more difficult the Nullifcation, with even moderate nullifications being of surpassing complexity. However, the ultimate potential for this ability is vast.
Gisena is very familiar with Findross, and Edeldross is a related energy, so she should be quite adept at manipulating them. Once she's nullified Edeldross into Findross, this would allow Coalescence. There might be issues with making a male sorceress, see the section below on the nature of findross.
There are ways to induce Coalescence as well. Just gotta get some findross or findross-equivalent energy!
We would be able to manipulate findross as well, though it might still be a ways in the future.
Speaking of ways to buff Gisena, the Tyrant's Rank buff would certainly get you closer to a relevant Rank for Accretion-based findross manipulation... this on top of the Arete and Curse mitigations!
My guess is that using Rank to produce Findross is the brute-force solution, where you're so powerful that you can manipulate just about any exotic energies, Findross included.
Anyways, that's my idea for creating and manipulating Findross, as well as Coalescing.
The nature of Findross
Findross is the concept of perfection. But then, who or what is defining that perfection? Luckily we have the answer to that.
"Yup! But don't worry, I think I've grasped a new aspect to the nature of findross. If I'm correct, the Foremost utilized it as well. Letrizia's work has been quite helpful on the matter."
...
Gisena paused, mulling over her next words. "The Maiden... is every Sorceress' role model, the founder of our civilization and source of all our Graces. To quickly advance in Sorcery, one should emulate her as closely as possible. Excellence in every field. Perfection in grace and poise. And, it goes without saying, remaining a pure and chaste maiden. Not to brag, but it all came easily for me. Many lords tried courting me, but none of them ever came close to keeping up, so it was easy to avoid becoming interested. It was easy to deflect them, easy to master the arts and sciences, easy to advance as a Sorceress... I never really faced anything comparable to what you did, since I portaled away before the Hero could begin his conquest. My home civilization may be doomed, but I've never had to see it burn. Would I lose my composure if I had?"
...
"Speaking of, I'm hopeful this new breakthrough will free me of the Maiden's shadow, allowing me to improve my sorceries directly! Though I'm not certain of the exact benefits it'll bring..."
In Gisena's world, the maiden defined the perfection that Findross worked towards.
Later, a hero orc of equivalent power rose up, and attempted to redefine perfection.
the Orcish equivalent of the Maiden
Both of these beings attained Findross Singularities, at which point the concept of perfection they were working towards became self-defined. The maiden became the perfect maiden, and since she held infinite Findross within her she re-defined perfection to being being her. Had the Orcish hero won, he'd have done the same thing, except perfection would be become being more like the orcish hero.
This universe doesn't seem to have ever experienced a findross singularity, or perhaps maiden-equivalents appeared and were immediately beaten up by astral lords or something. Either way, Gisena's advances mean that in this world we don't have to be a woman or an orc we're required to emulate in order to coalesce.
Of course, we could get a findross singularity of our own. Here is how we'd do it.
(consuming this fish ignites a meta-singularity of findross within you; should you survive then you may theoretically wield the True Quintessence)
Fish, and eating, are both very near and dear to Hunger's heart, so it should come as no surprise that these two acts lead to the Findross Singularity. Power is required, but so is a definition of perfection. Hunger eating a fish is perfection to him, all that is required in addition to this is sufficient quantities of Findross to latch onto this perfection and ignite the singularity.