Last December Paul Mooney posted this entry in his blog: "Customise ALL the client error messages for Notes". Among other things, he offers a database developed by Bill Buchan and Julian Robichaux, which gets all text strings of the Notes client in the currently configured UI language using a C api function.
But this database allows only for one language at a time. I've extended it with a language field and thus made it possible to store more languages concurrently.
For people using a non-English UI in the Notes client, searching for a error message in the Internet is quite difficult. The non-English version of the error message rarely returns much search hits. What's needed is not only a translation to English, but the original English message. And you can use this database exactly for this need now. Searching for the non-English text, you get a number. Using the number, you get the English string.
For this you have to download this database, unzip it, adapt the ACL, sign it and create a database from this template if needed. Then call "Create Error Codes" and wait. To get the English texts, you have to switch to the English UI, restart the Notes client and call "Create Error Codes" once again. This way you could import as many languages as you have Notes clients installed in.