It is nice that you define filters with your fields, problem is, that you missuse filters as actions. In docs you even call the filters “actions” and give them ‘action_’ name (e.g. http://www.advancedcustomfields.com/resources/acf-render_field/)
FILTERSs should always FILTER the output, you are just allowing to put something before or after the output – and this is what are ACTIONS for. Read the WP docs (http://codex.wordpress.org/Plugin_API#Hooks.2C_Actions_and_Filters)
