The game was built in Cerberus X, which automatically transpiles to various things, so I don't usually directly touch the libraries it uses to talk to the OS.... however, CSX is open source so we can just search it; this looks like it might be promising? I just searched Crescent Loom's repo to confirm that I don't mention libcurl anywhere else. I am using that httprequest.cxs file to talk to the creature server, so that might be a good list to pursue.
Sorry you've had to spend so long googling this! >_< I appreciate you posting the problems/potential solutions here. I'm also happy to keep assisting to the best of my ability, I'd love to see the game work on more versions of linux.