When my note's Title or Text's color is Black it appears as white.
Why does this happen? I think it has something to do with 'util.lua' getColorOrDefault() having "white" as the default color.

Screenshot: https://prnt.sc/ipa04x (Not just on warehouse, happens to every note)

I intentionally did that, because a black title is super hard to read outside of the text field. This applies to the note text aswell (black text is drawn white when you hover over the entity).

I could merge black and white into one color so the switching is less confusing if thats any better?

since black and white both behave like white, what's the purpose of offering to select black at all? if you don't want people to use black, can't you remove black from the list of selectable colors?

but if people absolutely want to use black, why shouldn't they be able to do that. if you change the default of new notes to be white (maybe even have mod settings for title default color and text default color?), people won't encounter the problems with badly visible black titles/text by default, but they would still be able to change color to black and then be responsible themselves.

Agreed. I removed the color replacement in version 0.2.0 and made white the default color. The text fields are now a bit darker to maintain good readability.