What is an indication of a successful transition to backup mode?

In the context of transitioning to backup mode on the A320, one key indication of this transition being successful is indeed that there are fewer protections available. This is because backup mode typically implies reliance on simplified systems that do not provide the same level of protective features that the primary systems do. In backup mode, the aircraft runs with limited functionality to ensure basic flight control while sacrificing some of the advanced protections typically available in normal operating mode.

The operation of backup systems is critical in scenarios where normal systems are compromised. Therefore, successfully switching to backup mode indicates that the system is operating within its capabilities, albeit at a reduced level of security and performance.

The other indications, like having normal functioning flight controls or continuous electronic feedback, would not apply directly to the situation of backup mode, as they generally pertain to the system's primary operational state. Cross-checking before flight is a procedural requirement rather than an indication of the system's operational status during the backup mode.