How to detect stuck relay in PLC?
If you have to be absolutely sure that the relay contacts have transferred, the best bet is to use a "Force-Guided Relay", or "Safety Relay".  They are made by various manufacturers.  On the FG Relay, use an extra contact as feedback to make sure that the relay has transitioned.

By design, FG Relays cannot only partially transition, even if one contact in the stack is welded together, the others cannot transition.

Even using FG relays, depending on the size of the motor, as you stated in your question, I would make sure that your direction switching relay only transitions when the power is disconnected to the motor.  That will eliminate some contact arcing.  Put some snubbers around the actual power switching contacts.

For what you are doing, that seems about the best approach with an electromechanical solution.  Depending on the size of the motor, you might do better with a small DC regenerative drive.

When all else fails (and from industry, I know it will), fusing is always a wise idea.