You are correct that the read capability is intended for the frontend. The capability you’re looking for does not exist.
Additionally, if it did exist ( which it does not ), the WP Admin user interface does not provide a UI for viewing/reading posts, only addition and editing.
If you want it, I’m afraid you have to take the following steps:
- Add a new capability, and add it to the relevant roles
- Remove the standard WP access to those custom post types for those roles
- Implement a UI from scratch, including a listing screen, and an option page for viewing the items