Clear plastic viewing windows on the spring terminals are the way to go. It allows for both instant feedback for the installer, and visual inspection or troubleshooting later by a third party.

The spring terminals should also be designed to have a secondary latch on this type on (what should be) rugged installation.

Finally, critical circuits should be designed to detect open connections, and act accordingly. A single hardware<->software design for this could be a module to apply across all such wiring inputs/outputs. This is simple and cheap enough to do these days.

A manual tug-test on the physical would be advisable when installing, to check the spring terminal has gripped the conductor when latched.