Change Caldera Forms field values using caldera_forms_entry_saved action. See: https://calderawp.com/doc/caldera_forms_entry_saved/

get-set-field-values.php

<?php

add_action( 'caldera_forms_entry_saved', function( $entryid, $new_entry, $form ){
   //get value of field with ID fld123456
    $value = Caldera_Forms::get_field_data( 'fld123456', $form, $entryid );

    //if value is a number and greater than 25 change field with ID fld42424242's value to "tacos"
    if( is_numeric( $value ) && 25 < $value ){
        Caldera_Forms::set_field_data( 'fld42424242', 'tacos', $form, $entryid );
    }
    
}, 10, 3 );