As to post 9 we can only suggest a path to your forum and that can only be based on the only path we find the one the script is running on so its always up to you to put the proper path.
As to post 10 this is why the server log with the actual error is crutial. Your application is installed. All the core files are reachable that I am seeing the issue here is your phrases.php file can not be found/ran etc. Internal Server Error is very generic. There is something that server does not like about the file. I mean is it the size of the file. its something for sure.
Your members area has nothing to do with this your good thats how I got your url