However, there are two issues. First, your file names do not match the names of the files we already have of your images. Game Courier mainly uses pieces in the cazaux/shako directory, which have mixed case names, and all your new files have lowercase names. So, your new images cannot be used as a drop-in replacement for the ones we already have. Second, these are all .bmp images, which is fine for Zillions-of-Games, but on the web, we normally use .gif. .png, or .svg images.
I unzipped the file JLCChess.zip to /graphics.dir/cazaux/, and you will find your images in
https://www.chessvariants.com/graphics.dir/cazaux/JLCChess/
However, there are two issues. First, your file names do not match the names of the files we already have of your images. Game Courier mainly uses pieces in the cazaux/shako directory, which have mixed case names, and all your new files have lowercase names. So, your new images cannot be used as a drop-in replacement for the ones we already have. Second, these are all .bmp images, which is fine for Zillions-of-Games, but on the web, we normally use .gif. .png, or .svg images.