By default, these programs all default to a method known as knockout, which means an overlaying color “knocks out” the color that is beneath. This is possible because 1) a lot of graphics are just for web use, 2) the image will be processed by RIP software just prior to printing (raster image processor).
The RIP software does just what the name implies, it converts your artwork to a raster. The equivalent would be saving your work as a PNG, JPG, EPS, TIFF, etc. Your printer is essentially acting like the Glowforge in engrave mode.
I think the Glowforge has some cloud RIP capabilities, but not extensive. And then it’s complicated by throwing in true vector pathing for other parts of the project you don’t want engraved.
Two things help a lot with seeing what will happen: the outline mode, which drops all appearances (strokes/fills/custom appearances) and just shows pathing. Then, you can see where paths overlap. You just have to remember which paths are filled and will be engraved and how that will impact the work.
The other is one I don’t think that’s been brought up here: overprint view. It might not be a great tool to use here since it requires a little bit of effort to set up and design with.
But, it will effectively show you visually where you’re going to have “overprint” issues… it simulates an overprint view that basically says, you’re going to overlay these ink colors and this is what will happen. I’m not an expert on it because I really haven’t used it much in my history with Illustrator - but it seems if used properly, it could help identify some issues.