From article Calibration XYZ (MK2/S)

Initial XYZ Calibration error messages

"XYZ calibration failed. Bed calibration point was not found."
= Printer was unable to perfectly locate the initial calibration point.

"XYZ calibration failed. Please consult the manual."

= Calibration point was not found at all.

"XYZ calibration failed. Left front calibration point not reachable."
"XYZ calibration failed. Right front calibration point not reachable."
"XYZ calibration failed. Front calibration points not reachable."

= Printer was unable to find Left, Right or Front calibration points.

"XYZ calibration compromised. Left front calibration point not reachable."
"XYZ calibration compromised. Right front calibration point not reachable."
"XYZ calibration compromised. Front calibration points not reachable."

= Your printer was able to finish the initial calibration. However, your Left, Right or Front calibration point was just in the middle of passing the calibration or failing it. That means you should be able to use your printer.

Mesh bed leveling error messages

"Bed leveling failed. Sensor didn't trigger. Debris on nozzle? Waiting for reset."
"Bed leveling failed. Sensor triggered too high. Waiting for reset. Bed leveling failed."
"Sensor disconnected or cable broken. Waiting for reset."

= Your printer was able to finish the initial calibration. However, there is something wrong with your P.I.N.D.A. sensor position.

Calibration Error Messages

XYZ Calibration error-messages (MK2/S)