How do I add multiple colors to the Color Palette at the same time and do so in a way that's more symmetrical?

What I mean is, I wish to add all of these colors in my ramp to make a New Color palette

And I also want them on a straighter grid, so I can tell which comes first

there’s no way to tell aseprite to make a new line in palette, so you need to use ctrl+scroll wheel to change the size of the swatches and/or resize the width of palette panel.

the easiest way to import all colours as gradients like in your image would be to use surt’s [Extension] Palette Utils
there’s a section ‘add indices’ and button ‘all pixels’, that does it.