I always just replace apk using fx through system (root) never had an issue.Are you somehow still S-ON with the rom? It wouldn't work if that's the case. You can also attempt to do it in recovery or if you have a PC, unzip the ROM, switch out the camera with funluan's, and re-zip it before flashing.
I went the way that gstanke went. Replaced using a root explorer, changed permissions and rebooted. Good luck.
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