A slaveworker was an incarcerated man who were sentenced to work - something like the Chaingangs in US.
It did not take much to be sentenced to slavework. He could very well have been a tailorjourneyman (not cooper journeyman?).
Boel was 22 and this Jens was ab 48 when Johanne was born, but he can still be her father. And we know nothing about the circumstances of her conception. This might be the reason of him beeing incarcerated - not a nice thought.
Or he might have done something stupid, served time in prison and when he was free again he found that the one he loved had married someone else so he got drunk and hanged himself.
Or he might be a quite different Jens.
Carl hanged himself. The last word was Aandsforstyrret = deranged mind.