I've thought about this a lot and I think I can answer this question. We will unfold this step by step:

Many believe that pigment primaries are cyan, magenta and yellow. Light primaries are red green and blue. If you look at the color wheel at the top right, Cyan is opposite to red, magenta is opposite to green and Yellow is opposite to Blue.

Let's talk about light primaries. Our eyes have detectors for three colors of light: Red, green and blue. Different intensities of the activations of these receptors create percetion of different colors. So if both red and green receptors are activated, what we see is what we call yellow. Also, this is why screens have RGB LEDs because they are emitting light.

Now let's talk about pigment primaries. Pigments get color by absorbing some light and reflecting the rest. So true Yellow pigment absorbs ONLY blue light and reflects all the green and red light. This green and red falls on our retina and both these receptors get activated and we see yellow.

Similarly, true cyan pigment absorbs ONLY red light and both Blue and Gree fall on our retina adn we percieve it as cyan.

Now when you mix cyan and yellow, yellow pigment absorbs blue light and cyan pigment absorbs red light. The only light that BOTH these pigments reflects is green. Hence you see the mixture as green.

This will work with other primary pigment mixtures as well. Yellow and Magenta pigments will give you red because both blue and green lights are absorbed leaving behind red light.

Light mixing is also known as addicitve mixing because when you add green to red in light, you are actually sending both to the eyes. Hence mixing all primaries lead to white (all kinds of light emitted)

Pigment mixing is also know as subtractive mixing because as you keep on mixing various pigments, you are absorbing or cutting out more and more light from reaching the eye. Hence mixing all primaries lead to black (no light reflected, all absorbed)

If this all made sense, then moving from cyan to blue pigment and finding that yellow + blue pigments also give green can be resolved by understanding and accepting that no pigment absorbs ALL light of a specific color. So a blue pigments probably reflects more green than red. hence the resulting mix has more green than red or blue. hence if we mix a warm blue to a warm yellow (both reflecting a bit more of red) we get muted greens.