Roles - Broken?

That is because gravityforms_edit_forms only allows them to edit forms. There is a different capability for viewing entries. That capability is gravityforms_view_entries.

The easiest thing to do is install something like the Members plugin which implements easy role management. Once activated you can turn on it's role management/editing capability on it's settings page (it's modular, only activate what you need). Then go to Roles under Users and edit a role and add the Gravity Forms capabilities you want to add to that role, they will all be listed when editing the role so you can pick and choose.

If you install the Members plugin and do this you may need to edit the Administrator role and make sure all the Gravity Forms related capabilities are checked.