Make sure you understand the difference between Module Portal Type and Document Portal Type
Modules portal type titles are part of the UI and shall be translated with erp5_ui. The
getTranslatedTitle method will use Localizer's erp5_ui catalog to
translate the title of the module document when displayed in the page templates.
Document portal type titles usually do not have to be
translated. Sometimes in a multilingual environment you may want to translate
document's title, in that case you should use erp5_content. Keep in mind that
this may add lots of messages in you Message catalog, and cause database size problems.