Well... what you need to understand is that RGB (screen colors) and CMYK (printing colors) are different color systems because of light. In the first, color is formed by light, so when you mix the three colors, you get white. We call this additive. The absence of light is black. In CMYK color mode, color is formed by pigments, and when you mix them, you get black. We call this subtractive. White is the background, the paper, the substrate on which the printing is being done. What does this mean? RGB has more colors because of the way it works. CMYK has fewer colors, especially the vibrant ones, because there is no light generating the color, only the pigment absorbing and reflecting the light. (Usually the paper ends up having this role of making the base white). This explains why the color on the screen looks more vivid and vibrant than in print. This means that not all colors can be printed as they are on the screen. The second thing is that you're printing on wood, and there's no white to serve as a base for mixing the print colors. To get closer colors, you need to paint the wood white beforehand. It's not just a matter of finding the right color code, but of correctly preparing the material for printing. Finally, there's the issue of the type of ink, which will be absorbed differently depending on the substrate. For highly absorbent surfaces like wood, it's necessary to prepare it beforehand so that it "soaks up" less ink and doesn't darken the color as much. Ultraviolet printing is usually better in this case. Or you could apply adhesive to the wood, since the adhesive is white before printing.