Some themes, like WPBingo, work together with page builders like Elementor and let you set footers or other elements like headers and templates via theme options or the WordPress Customizer.
For most footers and similar elements set via theme options, you need to tell your theme which footer to display in each language. This means that after translating the footer, you need to go to String Translation and search for the default language footer ID and add the secondary language footer ID as the translation.
