How can I add filter to footer-content?

Hello, thats my new Website --> http://wordpress.koehlerbau.com/ there is an email addresse in the footer (contentinfo) and i have install the plugin 'Email Address Encoder' (https://wordpress.org/plugins/email-address-encoder/) to obfuscates the email addresses! But it doesn't work to the footer-content... How can I add a filter into the childs function.php like: add_filter( 'catchbase_footer_content', 'eae_encode_emails' ); -> this also doesn't work Do you have a tip for me to solve the problem!