A few things I’ve observed about air combos and getting the followup:
In general, it’s easier to combo an L-talon after the H-scythe if X-23 is “in front” of the opponent, as opposed to “under” them. Which means the consistency of the air combo you do is more related to the** height you did your launcher** at than anything else.
Example: set the dummy to stand and just do Launch, H xx H-scythe, L-talon. It’ll combo, no problem, every time, every character. Now set the dummy to jump, and do the same thing. See how the air combo can be dramatically changed as a result of when you hit S? Sometimes you even cross them up midair! (For this reason, it’s sometimes better to do a neutral superjump for the air combo.)
For consistency: try to hit S to launch with as low a juggle as possible. This requires some matchup knowledge, as different characters will flot differently, especially during feint combos. If you’ve noticed that you’ve launched them a little too high, you might want to omit Crescent Scythe in your air combo unless you’re in the corner. Of course, if you absolutely need the damage, and you’re midscreen, practice delaying the L-talon after the Scythe. Be aware of what side you’ve ended up on as well - j.H will hit behind you, but you might need to input scythe and talon the other direction.
For the OTG: the leniency of getting a fully charged ankle slice is also related to how the air combo connected (and by extension, how your launcher connected.) The hitbox on L-talon is pretty wide - depending on what part of the hitbox spikes the opponent down, you might get considerably different spacing and “frame advantage” when you both land midscreen. Worst of all, this will be different for different sized characters (Tron, MODOK, V.Joe, and Ammy being the most notable examples in my experience).
(The most frustrating thing: hit your air combo, OTG ankle slice xx rage trigger - the ankle slice connects, but you’re too far away, and Rage Trigger whiffs. X-23 then gets punished and killed.)
A workaround: from what I’ve observed, there are actually two (or more?) types of “flying screen”, which changes depending on how high up you are on the screen. The “higher level” flying screens will actually cause the opponent to fall slower and/or stay grounded longer after an air combo ender (most easily observable situation: after an up TAC). You can take advantage of this by getting to “second level” flying screen by doing H-scythe at the apex of your superjump air combo. If you’ve gotten this higher flying screen (the camera will behave bit different), you’ll usually have enough time to add dash into ankle slice for a consistently spaced OTG (also more consistent assisted relaunches).
Takes practice, but IMO, it’s more important to take the random out of some combos. You never know when you’re going to run into an amazing MODOK player, and you’ll wonder why you can’t ever OTG ankle slice on him.