You have a two week duration task with 32 hours of work. The easiest method is to create the task with the 2 weeks duration. Change the task type to Fixed Duration. Then assign yourself and enter the 32 hours of work. Project will assign you at 40% and calculate 3.2 hours of work for 10 days.

Then when tracking you can either enter the percent complete. In your example below, you are confusing Actual Duration and Actual Work. It took you 10 days (Actual Duration) to do 32 hours of Actual Work.

I have actually completed the task in 32hrs, not the whole 2w (80h) allotted. Shouldn't the gantt bar for this task shorten and re-schedule successor tasks to actually start when the predecessor task finished after the 32hrs?