could be the picture quality, but #2 looks like oil deposit and #1 typical over-rich carbon deposit. Rich mixtures usually leave a matte, dust like look and oil leaves a semi-gloss, shiny residue. If I am correct, you may want to peak at the top of the #2 piston, as it would also be coated with oil residue if you are burning oil in that cyl. You can also see a bit of the oil residue on the end of the threads on 3/4, where there is not enough heat to burn it off. Just checking, but are the 1/2 plugs the same heat range as 3/4?
I have never seen a rotax so can't comment on possible causes of over rich on one cyl.
Larry