With everything that Bones/Foxlisk gave me, double shining is actually coming more naturally, especially since I've converted to clawing for it (thumb on B, index finger on Y). Consistency rate is sort of low, but that's just more practice.
How are you clawing it? Are you switching grips in the middle of play? That seems pretty bad, what if you want to eventually figure out how to doubleshine wavedash to chase rolls? Doubleshine grab? Doubleshine aerial?
Unless you're just clawing all the time in which case that would make a little more sense, but I wouldn't change grip styles for Falco's doubleshine, which isn't even very fast
It took me a while to work up the finger speed for grounded Fox doubleshines (not that I'm very good at using them, but I can do them!) but Falco's doubleshine is basically just making sure you don't rush the inputs
One super specific thing that I think you (and every Falco) should learn
Most Falcos will hit a tech then immediately up-b
Now it's nice that you're not just straight up dead ... but most of the time you're actually just straight up dead ... you don't even have the fire Fox has to help
So instead learn how to ledgetech illusion
If you think about the inputs, it's not actually very hard to do ... but you have to be absolutely mentally prepared to tech and instantly illusion
Alternatively ledgetech walljump -> illusion shorten, or at the very least delay a little before using your upb (moot point on Battlefield, but on stages where you can sweetspot from below it helps a lot to delay to the point where they have to guess if you're going to sweetspot or not if they're going to stay on the stage)
If you want to practice it, prox mine on the ledge in training mode works well enough
It feels like you get him under a platform with his back to the ledge and a fairly uncontested advancing laser a few times but can't capitalize ... I think this position is favored for you, but you have to keep track of what his escape options are correctly cover which one you think he's going to do
Also I'm watching game 1 of grand finals and I think I'm combining situations where he's on a platform with situations where you have him slightly cornered, but I think the point stands for both cases ... when you have someone on a platform you have the advantage in that at some point, they have to get off and your good attacks are very good anti air