Database problem - repair a bug with joomfish

We have a small bug on the website [login to view URL] We are trying to add a translation with joomfish. Unfortunately, there is a 500- An error has occur message. It also writes : DB function reports no errors The website works well. We don't know when that happen. We might have installed a module... we don't know. There are some words to translate, especially in the module section of joomfish. The person MUST repair it to be paid. It's probably something stupid but we don't know and are not specialists with SQL database. You have to do it in less than 3 days.