With the help of “Hi” (from #rgrd and the Rogue Temple forums) I was able to resolve the color space issue for Macs. Everybody on a Mac should be able to play Wayward just fine and dandy now!
Essentially, because I am loading in my static map through a color-coded .png file, there was some color space issues for various browsers detecting slightly different color codes. I thought I have accounted for them all, but I forgot all about Macs (not owning one and all). If you were having problems before, try it out now: