Took a look at your Speed-paint video, and I'm honestly surprised that you weren't using some vector art program like Inkscape to make all of this. Though, learning to use one of these programs could help you out a ton in the long run. You don't need to worry about resolutions, transforming objects too much, or even colouring for that matter, just the aspect ratio and translating a few filters can be a bit tricky.
The workflow of a vector program is also different, but if you need help with Inkscape I can gladly help. Pretty much everything I do now uses Inkscape for a good chunk of it. I only use Krita for things like lineart nowadays.
Also, quick tip that helped me a shit ton with colouring in Krita, and I'm pretty sure it's in Clip Studio is the HSV adjustment filter. Basically all it does is it adjusts all the colours on that layer. However, if you separate each colour to its own layer you can basically adjust every colour you have without needing to constantly re-paint over everything all the time. It's just a little tricky to dial the settings correctly if you have a colour palette that you follow.
But yeah, probably blathered on long enough, love your stuff dude!
