It sure sounds to me like you're talking about a lot of different things at once.
If you are printing using process color fills such as Bergen's or my Plotter Art™ Seamless Textures, you are not involved with any color palettes. Rather, you are involved with color modes, input profiles, color space, halftones and output print profiles. So, for fills such as Bergen or Plotter Art that are to be printed with process foils, I use the following and get very happy results:
- The color mode of the imported image should be RGB. It will be converted to CMYK when you output it. Start with RGB ... trust me.
- The input profile is best set in an image editor such as Photoshop and may already have been set by the publisher of the image. Your choice of Gerber [GSP] Default Monitor; Gerber [GSP] Internal Color Working Space; Gerber [GSP] RGB; sRGB IEC61966-2.1; Apple RGB; or Adobe RGB [1998]. They all work ... my preference is sRGB IEC61966-2.1.
- Set the halftone for most jobs to Gerbertone STC Photo and the LPI to 70.7. The higher the LPI the smaller the halftone dots but at the sacrifice of tonal quality.
- When you output the file, turn off Automatic Color Management and manually select the output profile named Gerber EDGE II 300 DPI CMYK. You will just have to trust me on this but following what I have listed here will give you customer pleasing results and will most closely look like what you are seeing on your monitor.
As the the other side of your post ... selecting colors from palettes, Gerber does any conversion to the closest CMYK match from any source you select. Select a spot color and then click on Fill tool and change from Spot to Process. You can also select Pantone colors from the same dialog if you prefer. You will also do well to choose a pleasant halftone pattern and LPI setting. I prefer Classical Dot and and LPI of 53 if gradients are present or 70.7 if the fill is a solid. Again, when you output, manually select the Gerber EDGE II 300 DPI CMYK profile in the 123 dialog in GSPPlot.
If your job is color critical, then do test swatches before you produce. You cannot expect thermal resins to match right up to solid color out of a Pantone book. There will be variations and halftone, LPI and output profile will all have an effect.
Hope this helps.
This may seem like a stupid question but I have to ask..