First this is a great plugin.
We are using it to schedule a cron task to import posts from an xml file.
We are by default setting the schedule to twice hourly.
When we edit the cron in plugin cron manager, the new schedule time appears, but the cron task is still running twice hourly based on the original setting.
WWe are competent PHP coders and are happy to help with further development of this plugin including some financial help if required as we see it as a very useful component to work with our plugin realpress.net