Sorry for being spammy, just an update on troubleshooting this issue. After realizing that I could manually type the key for each item on the Tying Equipment list, I used it normally, but then accidentally typed the key for the problematic Leather Rope. Didn't crash like always. I thought that the problem might be with the Encyclopedia being bugged and crashing every time it would display, which would explain why the rope didn't crash when I went directly to craft it, but would crash anytime the encyclopedia entry would display.
So I made a backup of my game folder, reinstalled the game for a fresh GAME.NFO, and restored my old modded game files but instead of the modded .NFO I used the brand new one. The issue was gone.
The weird part is that when I went to confirm this was the issue, and used the modded .NFO, the error didn't happen. So at least my game isn't crashing anymore, though you might want to check the Encyclopedia mod to make sure there's no issue with it and with the entry for Leather Ropes.