My two cents
Been in this hobby (can you call vaping that?) in and out for like 4-5 years. When I started, leaking was so common that we had a saying at the office stating something like "Q-tips and cleanex tissues are vaper's best friends"
Anyway, I mostly managed leaking issues back then when I switched from poly filled tips to the 510 ego-T atty. That thing would never leak unless the cartridge was over a month old and all worn out. Yet I never was really satisfied.... when batteries would go low, the atty just couldn't handle them and you would start sucking in eliquid.
Now that I've returned, I see great improvements like mods, VV and VW and bottom feeder tanks that don't leak nowhere as bad as they used to (I'm from the time we would rip appart a CE cartomizer and use the inner post/wick/coil inside a pre-cut seringe body to make something like a "rudimentar" tank lol. Anyway... I think we will still see leakage problems in the next 5 years or so (unless the FDA and EU shuts this whole thing down) because its not as easy to fix as we might think. We can't make air tight devices because no liquid would flow in and its th same component that lets ejuice through that is also the main seal in any tank... the wicks... too much and you get dry hits, to few and you get gurgling... its a matter of balance. Problem is that we live in a dynamic world. You're working with AC at 23C and 30% humidity... you go outside and its 32C and 70% Humidity... you get into your car and... you get my point. Variables are changing and a simple wick just can't "adjust" itself to those changing conditions.
I'm sure that in the future some clever guy (chinese or any other) will come up with an alternatve to common wicks... something like a venturi type eliquid feeder that will let just an X amount of fluid go into the coil no matter what you do but until then, all one can do is get his hands dirty and rebuild, experiment and rebuild again. I've done countless rebuilds and I'm playing with wicks and coils. I had many suceed and other that failed miserably. I found out that what works for some on youtube videos just doesn't work for me because of hidden variables (ambient temperature, e-liquid, battery, etc). You just need to experiment until you find something that works for you.
All in all... this is a messy hobby... kinda reminds me of those old documentaries about cars... I'm pretty sure that in the early day, cars would break down a lot more, have wierd engine problems, fuel flooding etc... it took 100 years to iron most things out and there are billions and billions of cars out there... we are just a few millions and most of us aren't even interested in tinckering with this stuff... we just want to vape and vape well (I wish I could do the same). It will take years so unless you want to return to analogs (as I once have done and I still regret it), start working in solving your issues
Good luck
Regards
Tony