Thanks for your answer @v-bacao-msft
My Sharepoint list contains 2 date and time columns ( VacationStartDate and VacationEndDate ). Thanks for the input, I'm currently working to get a Calculated column directly in SharePoint list.
You can find a full screen of my flow below, my problem is really how to make the harvest connectors to work.
First, how to enter my VacationStartData and VacationEndDate to get harvest to create a time in the good dates (start and end); And second how to create an entry on behalf of someone else.
More details: you can find my actual configuration on the harvest connectors below. What I'm getting is an only entry in the start date with the amount hours that I forced typed, since I don't have the calculation yet, and the harvest entry is always under my VacationStartDate it doesn't consider the VacationEndDate. And the Harverst entry is always under my user on harvest, it doesn't considers the user get before in the Get user info (harvest connector before).
Original sharepoint request:

Harvest connectors:

Harvest Entry:

Full flow:

Thanks again if someone have an idea.