The KoF and FF continuities were pretty much always treated as separate - with the Ash story involving time manipulation, now they have an excuse to explain all those oddities - or add new ones, like the Samurai Shodown and Last Blade characters in the XIII stages.
It does, the Garou intro specifically references Terry’s Real Bout ending.
Also, Kyo shows up in Bob’s FF3 stage - I think Kensou does too. Choi also shows up in Kim’s RB2 stage.
The closest to that was MI2’s use of alternate character verions, and character skins that referenced different characters - there was a Syo skin there, but I don’t recall if it was assigned to default yo, or the Classic version.
If they were to make a new dream match based on current assets, I suspect they’d prefer to actually to go with a renewed Adel than Rugal. He almost made the cut, based on soe illustrations, not to mention story mode presence. I really don’t see Saiki being implemented beyond his already playable self…
Considering how they’ve depicted him since 2003, it seems entirely intentional - one of those thing when they try to get plot and moves to match to an extent, like claw Iori.
Other than Iori’s 95 team and the 97 special team of Yamazaki, Billy and Mary, there’s also Chizuru’s 97 team, which consists on her, Mai and King.Also, Malin teaming up with asumi and Eiji in XI.
Yeah, those characters tend to be secondary, but KoF is where a lot of their character development has continued outside their source series - on the AoF side of things Yuri’s gotten a lot of development there, running circles around her family to get to do her own thing, the King & Ryo relationship gets developments and pushes there were practically absent in AoF.
KoF has been running on comic book time since 95, the last year where KoF characters actually aged (so Ralf never got to be 40).
Unlikely IMO, although MI2 did get a couple of nods in XIII, with Lilly using her alternate outfit from that game in Billy’s stage, and Elisabeth getting a Mignon palette.
MI just went in too weird a direction, with aliens and whatnot, and pushed its own original characters too much to the forefront. Still, I could imagine some character gettings nods, like Chae Lim in some Kim cutscene, or that Hizoku girl that appeared in KoF MIRA, Xiao Lon getting a brief reference, since Ron and gang are being built up as major story players for future installments.