Sorry, for the very late reply. But I've updated the site. You have scroll to very bottom to see the RomHackPlaza gif with the clickable link. Here is the image for poyosoft.xyz which is the same size image as that Final Fantasy site. (Also you may have to clear your cookies as the site may not...
Same here, I mind people releasing unfinished work but It would nice if they at least update it overtime to end up making finished Rom Hack. (Can I really be talking though... Boxguy in SMB2 is still unfinished. I got to finish that ending art.) Still a cool demo!!
I think it's your emulator because I play with FCEUX on PC and Retroarch on Mobile and i've seen no such crashes. Plus that boss fight was unchanged from the OG Kirby's Adventure. (Also the latest version works with latest emulator update for me at least...)