This is an unfortunate hole in the specification around user configuration settings. You are correct that there is typically a way to verify the configuration. This is normally through page requests, however in some cases it is available through page 71 for FE to handle additional complexities. Neither of these is specified for page 55.
In General: Acknowledged messages not being sufficient is typically only an issue in cases with multiple controllers, when new controllers are connecting to an existing configuration and want to maintain parts of the configuration, or when a command cannot always be handled.
For FE User Configuration: Only one controller should be attempting to set the user configuration, should set it fully when initially connecting, and should update the configuration whenever the user makes changes. As far as I am aware there is not a case where the user configuration cannot be applied. Therefore, depending on the ack is relatively safe.
In SimulANT+ page 55 can be requested. Some devices may have copied this behavior and support requests for page 55.
