Bonjour Raphael
I'm sure no damage has occurred due to your brief exhibitory run!
Many stationary model steam engines, of many well-known brands, have no provision for oiling what-so-ever and run for the better part of a century without any significant wear or damage!!
Yes, low pressure saturated steam is essentially self-lubricating, and so I'm certain sure that Jin's superb little machine is absolutely fine!!!
Just wanted to know if that was actually an oiler, or just a decoration, and if it was indeed connected to the inlet port. You have answered my question in detail.
Now I wish to ask if perhaps you have a boat small enough to make use of this little gem by Jin??? ;c)