Based on the missing language string, I would say something happened that the patch did not apply correctly. I recently made a quick attempt at applying the patch to my git repository which you can check out at https://github.com/arborrow/moodle/tree/moodle19-patch_forumpostapproval. I have not tested it much but it may be a step in right direction for you. If you are familiar with git then you can pull the code in. Otherwise, if you just want to test it, you could download the zip file and install it on a test server and see if it helps. I'm attaching the results of a diff between MOODLE_19_STABLE and the version in the git repository if that might be of help.
I also began looking at migrating the patch to Moodle 2.0. I've created a branch and would be willing to pull in changes as folks recommend them. Because of the more integrated rating system, we will need to redo things to get ajax working or simply decide to drop that functionality. It is not likely that I will have much time to mess around with it so if folks who are using it want to begin helping to adapt the patch to Moodle 2.0 that would be most appreciated.
Let me know if you have further questions and how I might be of help. Peace - Anthony