Thank you for your interest in UI for NativeScript.
DataForm is a new UI component and have
some limitation. Indeed such a method, which checks, whether the entire form is valid will be useful. We verified the suggested functionality and it is planned for the next nativescript-telerik-ui-pro release. You can expect that in early 2017, though I cannot give an exact date.
You could also keep track on the new features updates and fixes in our Release notes section. We also have dedicated "What's new" blog article which can be found here.
Hope this information helps
Telerik by Progress