Change woocommerce order status by database change

I have a dropshipping client who uses Delphi in his company. He connected his system to my wordpress database and can read and write it.
The WordPress site runs on a windows server.

How can I make sure that when he makes specific changes in the database the order will be changed by script? (processing -> completed)

In the first place I would use the php/javascript/python api, but how can I make sure it will be triggered automatically by his database connection?

The best solution would be if the database change alone triggers the order status change with all its functions, like customer email etc.

My ideas would be:

What are your ideas for a stable and reliable solution?

No hate please im a beginner. I appreciate any ideas and solutions.

Thank you