The one in the default template looks ok, it's hard to tell on the others. The PHP side is the same for all. As per the code in templates, it's just HTML. If it doesn't show the links... well, I guess there should be something missing.
There are countries where people may speak several languages. Wouldn't it be better to rely on user preferences? The browser sends the preferred language in the request headers, you get read it from $HTTP_SERVER_VARS['HTTP_ACCEPT_LANGUAGE']. In the PHP manual there are some examples on how to deal w...
BTW, you could optimize your import dump by removing the INSERT statements related to the phpBB search tables (which are probably the biggest tables in phpBB) and then, when your new board is ok, rebuild those tables from the ACP.
If you don't have MODs installed (ie. the DB design is still the standard), you could probably In your source environment (MySQL): Extract a DB dump with INSERT statements only. Make sure all INSERT statements are ordered by table name. Before a set of INSERTs for each table, insert a SQL statement ...
Have you tried to copy the test.php script in other directories? Still the same results? Then he could move the test.php script to another folder and try a similar check. Maybe there's somthing weird affecting only the folder where his phpBB files are stored. Such a test should clearly show the host...
Oh, there is something that you may want to review in your code as well. All BBCode MODs ought to be compatible with the Multiple BBCode MOD, otherwise the MOD validation would deny it.
The Multiple BBCode MOD will make your MOD much easier to install.
Could you please edit your topic title with a prefix as outlined in MOD Development forum rules section 3.a. This will allow people to see the development status of your MOD at a glance.