Well, it is clear that everyone in the group is either a dragon, an immortal elf, or someone intimately connected with them.
Sheila Blatavska is confirmed as Hecate and Miss Tick in Loose Alliances. As for whether or not she is Alachia, if she isn't, then she has to be another of the immortal elves, because in Loose Alliances it says she shares a relationship with Ehran and Aithne, and dressed down Schwarzkopf in front of his students telling him that he was teaching them wrong, and he should know better. Alachia is at the top of the list, especially since the other major female IEs are either Aina Dupree, or are working directly with the two Tirs or other awakened nations. Though, of course, there could be ones we don't know about. Another reason I believe Hecate is Alachia is found in the Aztlan file, pg 68. They are talking about Corruption, and Laughing Man says clearly that Hecate ought to know what it looks like. I take this as a pointed jab at how the Blood Elves had to Corrupt themselves to survive the Scourge. Again, same file, pg 172, she says this age is tame compared to the last one.
Umsondo may be one of the Heavenherds, or he might be the Australian IE from some of the early novels.
Regarding Jungle Cat, the poster is clearly based in Amazonia, and is well versed in their internal affairs. I'll run through my reasons as they appear in the book, for easier fact-checking. I'll be including page references, as well.
Pg 11. Not definitive, but Jungle Cat's reaction to the mention of Aztlan is markedly more hostile than the others.
Pg 12. He calls Lady of the Court, Hecate, and Laughing Man juveniles. Again, not definitive, but it suggests Cat is a good deal older than Hecate or Laughing Man, and certainly older than Lady of the Court. On the same page, Cat doesn't get the reference to the 400 pound gorilla joke, claiming to not have heard it, while the immortal elves all know it. Circumstantial, but these two tidbits suggest that Cat has been, shall we say, under a rock the last few centuries or more. Further evidence is just before Big 'D' begins the file, calling Aztlan 'our ancient foe'.
Pg 21. When talking about Pobre, Big 'D' reckons that he is a lesser (not a Great Dragon), but Cat counters 'Perhaps in form, but not in spirit.' Only a fellow dragon (one might say only a fellow great dragon) could get away with that kind of comment, IMO.
Pg 22. 'Do we look stupid?' Jungle Cat clearly marks himself as a core entity in Amazonia.
Pg 60. Jungle Cat apparently knows enough about dragon magic to say he has not seen any direct evidence of it in play
Pg 61. Cat mentions going into Aztlan in his 'guise'. While this could be a simple mask spell, it suggests the great dragon ability to take on a metahuman form.
Pg 86. Again with the 'We', referring to Amazonia. Clearly a major player in the Amazonian government, and we all know how many of those there are.
Pg 102. Jungle Cat speaks of using sentients and dragons to summon blood spirits in surprise, since he thought it 'too soon'.
Pg 109. Lady of the Court asks Cat if he get's grief from the Corporate Court, and Cat says yes, for the same reason she does. If, as we believe, Lady of the Court is Brane Deigh, leader of Tir Nan Og, then the reason the Court gives her grief is because the Tir hasn't signed the Business Recognition Accords. Neither has Amazonia. This implies further that Jungle Cat is the leader of Amazonia.
Pg 114. Both the sidechats pretty much scream that Jungle Cat is in charge in Amazonia.
Pg 172. Has some... unkind words to describe Hecate, saying she has no right to be speaking to them.
All told, there is a very strong circumstantial case that Jungle Cat is a (if not the) key figure in Amazonian affairs. The list of key figures in Amazonian affairs is incredibly short, especially when you limit it to immortals. Hualpa is the obvious pick from this list, though there is always an outside chance it could be Sirrurg, the third dragon from Amazonia's founding, or another, unknown IE (though that is exceedingly unlikely).