It sounds like your setup thinks it is the US version (the EU version used client_local_EN_GB.dat for English, the US uses client_local_English.dat). In the LOTRO directory there should be a file called TurbineLauncher.exe.config, the EU one should contain:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<system.windows.forms jitDebugging="true"/>
<startup>
<requiredRuntime version="V1.1.4322" safemode="true"/>
<supportedRuntime version="V1.1.4322" />
</startup>
<appSettings>
<add key="Launcher.DataCenterService.GLS" value="http://lotroeugls.com/GLS.DataCenterServer/Service.asmx" />
<add key="DataCenter.GameName" value="LOTROEU"/>
<add key="DataCenter.DefaultCenter" value="LOTROEU"/>
<add key="Product.DocumentFolder" value="The Lord of the Rings Online"/>
<add key="Launcher.DocumentFolder" value="Launcher"/>
</appSettings>
</configuration>
If yours is different to that take a backup and replace it with the above see if that helps.
I've not had any of the other German users (or French for that matter) getting an error like that, so I'm guessing it is passing the language code to the game client correctly, I'll have a look to see if error 202 is reported on either the US or EU sites.