Hi Filip, 

Let's address these issues individually:

1. "Timesheets cannot be created on a private task." error: This error typically occurs when you're trying to create timesheets for tasks that are marked as private. In Odoo, private tasks are restricted from having timesheets associated with them. To resolve this, ensure that the tasks you're trying to import timesheets for are not marked as private. If they are, either make them non-private or select different tasks for the timesheets.
2. "Found multiple matches for value 'Meetings' in field 'Task' (7 matches)" warning: This warning suggests that there are multiple tasks with the name 'Meetings' in your Odoo instance. When importing timesheets, Odoo is unable to determine which 'Meetings' task to associate the timesheets with. To resolve this, you need to specify unique identifiers for each task. If there are indeed multiple tasks named 'Meetings', consider renaming them to be more specific (e.g., 'Weekly Meetings', 'Monthly Meetings', etc.) or ensure that your import file includes unique identifiers for each task, such as their internal IDs.

By addressing these two issues, you should be able to successfully import timesheets in Odoo without encountering these errors.

Hope it helps.