Almost a year has passed. I did not foresee that the bug I spoke of the last time would be that hard to fix.
OK, life took its toll; the last months have been difficult. But that's no excuse, I failed to fix the bug. My analysis was wrong; in fact it seems that stdout is opened more than once. I never found out the actual cause.
Circus is dead. As always my sin was greed: I wanted to build a full stack instead of concentrating on my application.
Let it be a lesson. If only I could learn it.
So I decided to start again with a stack I am comfortable with: Java. Everything is provided by external libraries, it is only a matter of plugging things together.
The application already works… "on my laptop". I am currently packaging it before launch in a few weeks.