It seems a build after v4.7.0pre9 broke the config files (probably v4.7.0pre10). I had an issue on my client where the config file would be overwritten every time I tried to start the game. This was an issue because I also had Mariculture installed, which has a conflicting enchantment ID. Doesn't seem to happen on the server.

Steps to reproduce:

1. Install Mariculture and ProjectRed on a fresh client profile (using forge-1.7.10-10.13.4.1614-1.7.10)
2. Start the game
3. Error: conflicting enchantment ID: 80
4. Change the enchantment ID in the config file to 101.
5. Start the game again
6. Error: conflicting enchantment ID: 80

Reverting back to v4.7.0pre9 fixes the problem.

Ah you called it. I was copying an old file and didn't think about other changes. My apologies.

Is the config file fresh? Or are you still using the same one from old versions?