Well, I can explain why you're seeing moments of yellowness.
White Dove belongs to the yellow hue family - right around the middle of the yellow hue family. The fact that it shows a little yellow/creamy in certain light isn't surprising.
Architectural paints aren't categorized by "undertones". They're categorized and ordered by hue family. Because when you correctly categorize paint colors by hue family you can plot them on a color wheel like this. It literally draws a picture so you can better understand a color's characteristics, for example, White Dove.
Knowing where White Dove belongs on the color wheel and what hue family it belongs to explains the moments of yellow you're seeing in different rooms. Also, having it mixed in another brand could have something to do with it. The balance of colorants in the custom match could lean more yellow than an original White Dove mix from Benjamin Moore.
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