Easy patch to make this more compliant with local/languages ...

I changed the following line to make this nice module compliant with language translation ... through the t() function
(line #63 of custom_add_another.module file)

$form[$field_name][$this_langcode]['add_more']['#value'] = t($instance_settings['custom_add_another']);

I hope this is right, and that might help ... and included in next module release