Why does WorkElement save work for session user ?

Ok, so, what I want to do is when I press the stop work button from my bot, it saves the worktime to the user who pressed the button and not the bot user. This means I can't just use the stop method from WorkElement.
I copied what Projeqtor does when you save imputations from the dispatch menu in hope it would work for me. Unfortunately, there is some strange behaviour.
Indeed, when stopping after some time, the amount displayed in the real work box is correct. However, if I open the dispatch menu, I can see a line for the user but with the wrong amount of work. I supsect the time is not converted properly and that time in work days is added to time in hours.
Perhaps it's because of WorkElement::updateAssignment. Does it need time in work days or in hours ?

I hope this explains a bit more my problem.