thanks for the tag.
sounds like you already have a sound feeling for jumps.
I agree knowing how to cork 7 and double backflips helps. But it's not that just that alone.
First of all you have to ask yourself what is easier for you, can you imagine the dub10 or dub12 better in your head.
There is quite the difference between them and the dub 12 is by a lot easier compared to a dub10.
Having solid cork 3's will definitely help you towards the 10, if not your best of going for the dub12 first.
To me, a double cork 10 is an overthrown cork 7. What i mean by that is, you don't really put more energy into spinning but you increase the amount of how much you dip with your upper-body (reference this dipping in my Cork 7 tutorial) so you pump enough momentum into your rotation - that you will actually go off axis twice.
You're goal on the set is to complete the first cork at around 630° / latest 720° (not ideal tbh) and then fall into the 2nd set of cork. People that usually try it out the first time - really struggle to freeze here and sway around with their head upon going into the 2nd cork. This will force you to go for a 12 by the way. They key for a d10 is to basically overset a cork 7 and then freeze and wait - spot with your eyes and don't move your head to the side (on the 2nd cork) , rather tilt it back like on a backie but not as extended - just slightly.
There will be tutorial(s) in February (currently scheduled) on how to double cork 10 & 12 the easiest ways - explaining this trick here is just too gnarly.
However - what i can recommend is , finding a trampoline near you and practice just that one motion. Do a cork 7 - steep corked - and keep your knees tucked and just over rotate it to your back and pop off from your back to a continuing "flip / cork 3".
If you understand this mechanic - you're good to go. You should be able to realize what the key part is there - throwing enough to the back whilst not completely forgetting about the spin.
Coming back to your initial question:
The Leap is not that big technically wise - Cork 7 and Dub 10's share a fairly similar set.
The biggest challenge you'll have to face is to be ready for it and to understand what makes it work as a double.
I'd suggest watch some double 10s - i dont want to sound douchey here but i've got quite a lot super slow mo dub10s on my socials. They'll show you quite good on what your arms and head have to do.
Speaking of proper detailed help by me - you'll have to wait for my tutorials ^^
Hope this helped answering your questions.