There's probably a conflict with the graphicsType variable; using fen2 requires that it be left undefined, and using the icons directly requires it be set to SVG, while the Galactic set you're currently using is GIF and needs it to be set to that. I don't know what file format Joyful is, but whatever the case they need to all be the same.
In this case, I'd recommend using https://www.chessvariants.com/cgi-bin/fen2.php?s=50&t=Greenwade&w=DDDDDD&b=339933&p= to make your icons one by one, saving the PNG files that result. Then you can convert them all to GIF using anyconv.com or whatever else you prefer, and upload the results to the game's files area.
There's probably a conflict with the graphicsType variable; using fen2 requires that it be left undefined, and using the icons directly requires it be set to SVG, while the Galactic set you're currently using is GIF and needs it to be set to that. I don't know what file format Joyful is, but whatever the case they need to all be the same.
In this case, I'd recommend using
https://www.chessvariants.com/cgi-bin/fen2.php?s=50&t=Greenwade&w=DDDDDD&b=339933&p=to make your icons one by one, saving the PNG files that result. Then you can convert them all to GIF using anyconv.com or whatever else you prefer, and upload the results to the game's files area.