After doing what was described in the title, I could not enter the world (others were fine) until I used an external application to remove the cog from the save entirely (I used the Amulet Editor for anyone else with this issue).

Crash report if it helps:
crash-2024-02-12_20.24.37-client.txt

I have no knowledge of Java or modding so this next bit is a complete guess made by looking at a couple lines of the crash report: I think the game is trying to render that connector bit that appears when you put a large cog on a speed controller. However, I don't think that model exists for the modded cog so the game crashes. But again, that's just a guess.

same problem
crash-2024-02-19_15.05.48-client.txt

same