The perception of color, even on a "Platonically perfect" monitor is, of course, entirely subjective, so my judgment as to how it looks is not the final word on this, no matter how great may be my monitor or experience.
My monitor is a 30" NEC 3090, calibrated with NEC's SpectraView II and their proprietary color meter. The background gray paper looks slightly magenta to me as well. The child is a different story. She looks fine, but would probably still look fine with the overall color adjusted to yield a more neutral gray on the background as well.
Anyway, to more precisely dispense with your question, in Photoshop's RGB info panel, a random spot on the mid-left side of the paper reads 58,55,62. This means, among other ways of interpreting it, that the paper is more red, and especially more blue, than a true neutral gray. To correct for that, you'd have to adjust the image with just a tiny bit of cyan and just a little more yellow than that. But, one must also ask, what is the actual color of the paper? No-seam paper is rarely spot-on neutral gray, so these measurements merely give you a good clue as to the "trueness" of your color balance.
As for my taste, yes, I'd like to see just a bit more yellow in the image more than anything else, but too much will spoil the girl's skin tone. As far as adding cyan is concerned, unless the subject's complexion has that ugly red skin blotching characteristic of many off-color digital people pictures, go real easy. Just a little too much cyan can turn what looks like a healthy girl into a sickly-looking one. And the young lady's complexion already looks fairly good in your example.
Last, don't forget when shooting people and judging clothing color, that some fabrics, due to the dyes used to color them, may phosphoresce when exposed to some wavelengths of light, so that no one color balance can get both that particular fabric and other picture elements such as skin, to look balanced with just one overall setting; locally selected areas may often need to be changed differently than the overall color.
Good luck,
David
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Keep learning; share knowledge; think seriously about outcomes; seek wisdom.
