All Odoo Spreadsheets are bidirectional, meaning you can get back to the source data.

For a cell linked to an editable field (in this case the budget would be in draft) you just right click it and access the See Record(s) option from the Context Menu.

You are then returned to the Odoo backend where you can edit the data:

The Odoo Spreadsheet will refresh the next time you open it, or you can trigger this manually: