Line chart for different countries for different period

Generally, the way to get around the limitations of the line chart is to write separate measures for the values.  So you might start with 2 measures: one summing the Actuals and one summing Forecast.  Put them both in the Y-axis section.  You can change the line type in the 'format' section (dotted or solid, for example).

It would be great to put Country in the Legend but it won't let you.  You can use Small multiples or add a Country slicer if required.

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There's an alternative solution if you re-organise the data :

https://exceleratorbi.com.au/plotting-2-columns-on-the-legend-of-a-chart/ 

Have a look at these and see how you get on