In some circumstances, it is critically important that colors appear identically in two different environments (say, on a computer screen vs. when that same image is printed on a color printer). Whole businesses and people's careers are based on working that out.
But most of the time, in real life ("IRL"), we can live just fine with "close-enough" approximations, because nobody cares to get that picky about it. Especially with something aesthetically pleasing like a painting -- who really cares if a photo of the painting doesn't exactly reproduce the pigment colors when the photo is displayed on a monitor? The important thing is, does the painting, or the image of the painting, convey a reasonably accurate expression of the artist's intent, and does it evoke emotions or other reactions in the viewer that are something like what the artist intended. Art is not RGB, or CMYK, or wavelengths.
Of course, wearing my (50-yr old) physics hat, all those technical things are of compelling importance. So it all depends on the context.
But there are probably many more people for whom this is a hobby, have no intent of ever selling their work, and for them, there shan't be any reason to worry, nor even think about such things as how anything is going to look on any kind of screen.
I paint because I enjoy painting.
Yes, I have taken requests from family and friends, but they don't get to see anything in progress. They know my work ( have seen a lot of it in person ), and I don't mind doing something for them gratis. I get to enjoy painting whatever it is and they get to have it mounted and framed. It's a win win for everyone.
Yet funnily enough, I never have framed and hung any of my own work. As the old saying goes: "The cobbler's children go without shoes."! In this instance it's the painter has hung other artists' work. ;^)