Can I add arrows to a calc graph?

I have uploaded a calc spreadsheet to
http://jimberry.org/files/files.html
It contains an area graph in which I have set transparency to 50% for the data series colours, as I want to see all the values in all 5 layers.
This makes the colour coding for the data series legends a little more difficult for a viewer to interpret.
Is there any way to insert arrows to point from a legend description to its associated area?
Or if not, can the vertical order of the legend be inverted to reflect the graphs appearance?

As a separate query, I can’t see how I have managed to get the value of cell C19 printed on the graph?

Ubuntu 17.04 - LibreOffice calc 5.4.3.2

Regarding the value for C19, did you inadvertently enable “Insert data labels” for that one value?

21/03/2019 - I have now managed to change the area colours so that the overlaid colours (50% transparent) are not as markedly different from the solid opaque colurs in the legend.
I would still like to know if it is possible in CALC to add arrows to the calc graph as shown in the attached png file where the arrows were added in LibreOffice DRAW?

@ve3oat - that is quite possible - but that stray value has disappeared after adding more “date” rows and changing the legend position to “top”

Sorry, I hadn’t worked out how to attach a file. The file mentioned in my first comment is at http://jimberry.org/files/march2019energy.jpeg and I have also included it in the page linked in the original question
Sample chart

I have found a simple solution on page 160 of the official calc guide

Select the Drawing toolbar (View > Toolbars > Drawing) which will appear at the bottom of the spreadsheet. Choose the appropriate arrow from the dropdown selector and draw the arrow where you want it to appear.
I have also changed the area colors and transparencies so that they are closer to the solid colors in the legend list.

Here is my example of how to add arrows to a calc chart.