I'm too married to my original cube. This cube is its own thing.
Time to reevaluate it holistically again...

...From the top...

What do people expect from a cycling cube? The most well-known tournament-level iteration is probably Living End, so a cascade/suspend package to live that dream seems great. Next is absolutely Astral Slide/Drift, so that's in alongside as many other good build-around enchantments/there are that specifically call out cycling.

From there, what are the components of cycling we can leverage?
Draw triggers. --> Faeire Vandal, Jolrael, Irencrag Pyromancer...
Discard triggers. --> Brallin, Bag of Holding, Bone Miser...
Creatures in the graveyard. --> Spider Spawning, Reanimator...
Non-creatures in the graveyard. --> Delirium? Spell mastery?

So after adding a lot of those cards, here's where the identities stand...
RG - Cascade; with minor trample, 3+ power, and "lands in GY" themes
BG - Spiderspawning and recursion
GU - Cascade & draw triggers
UR - Looting / Spells

(Notably, 3/4 green pairs are listed, but none in white.)
Which brings me to emergent strategies based on a lot of the cards "locked" in that color:

WU - Enchantments / Historic
There are a lot of cycling payoffs in these colors that are enchantments, plus Ardent Plea matters more in this context, so it seems sensible to build around enchantments. That's not really enough, so taking inspiration from Glassdust Hulk, "Historic" captures as much overlap as we can here. Of note, there's also a minor blink theme in WU with Astral Slide and Escape Protocol, so keep an eye out for cards that play into that.

WG - Might as well finish the last green pair. There are a lot of options here (+1/+1 counters & enchantments tying for 2nd, but there's also tokens, threshold, hatebears...), but to manage the balance of white's odd split between aggression and control, and green's giant creatures with cycling, I'm going with some aggressive ramp. This supplies it with card advantage, let's it capitalize on the karoos better than the other colors, all while applying pressure. In theory anyway. We'll see how it goes.

BR - This one's less clear, but since there's a reasonable amount of discard triggers in red (and so also some flashback), and black wants stuff in the graveyard for spider spawning anyway, I'm going to start by trying to make this the Burning Vengeance deck. Chainer, Gravecrawler, Squee, Dreadhorde Arcanist, and retrace help to suppliment Flashback and Aftermath effects. Madness was another option, but just didn't seem strong enough (too much of A+B). Sacrifice seems OK, but pretty disconnected from what all the other themes.

So to recap...

WU - Enchantments/Historic
UB - ??
BR - Vengeance
RG - Cascade Aggro
GW - Lands
WB - ??
BG - Spawning / Reanimator
GU - Cascade Value
UR - Looting
RW - ??

UB Self Mill:
Though still missing a WB theme, Black so far really wants stuff in the graveyard. Blue so far is also great at drawing a lot of cards. Combined, a UB self-mill theme seems like a snug fit.

WB Blink:
White has a lot of blink potential in its two themes so far (landfall, sagas); black has the unearth ability, which both plays into its BG, BR, and BU themes, but is a very sneaky way to abuse those blink effects and keep your creature forever. It can also reuse ETB effects just by bringing creatures back from the graveyard.

And then there was Boros...
RW+ Cycling was a fun Ikoria Standard deck, but a miserable draft deck. The biggest offender was certainly Zenith Flare, and while it might be an appropriate power level here (maybe not) I'm OK never seeing that card again in draft.
That said, there's not much other overlap between the two: red wants to discard aggressive flashback spells; White wants to play aggressive historic ETB/landfall cards. Boros will take some experimenting, but for now I'm just leaning into its aggressive side with some combo potential: Zirda & Feather. Zirda is obviously great with cycling, and Feather is pretty good with the blink instants in W and a few spells in R. We'll see where this goes.

So...
WU - Enchantments/Historic
UB - Self-Mill
BR - Vengeance
RG - Cascade Aggro
GW - Lands
WB - Blink
BG - Spawning / Reanimator
GU - Cascade Value
UR - Looting
RW - Zirds of a Feather

And this is our new baseline. There's enough complexity to allow plenty of other decks than just these 10, but beyond the primary pillar of "good with cycling", this at least provides some secondary pillars of cohesiveness to center future changes. Because it's such a huge overhaul, it's still going to need quite a bit of analysis before settling, but it's at least a better starting point than a completely different cube.