There is something wrong with the way Amaya handles copied text in the source view. 
It should differentiate the selection of loose text from the selection of lines in the source view. 

For example, a test case:

1 Open source view
2 In a line with text hit "home" so the insertion point sticks to the left margin
3 Holding "shift" press the down arrow: a line is selected precisely
4 Copy the selected line ^c
5 Move the insertion point to the beginning of another line, for example using the down arrow several times
6 Paste the copied line ^v

The result is that the text of the copied line is inserted before the target line´s.
The expected result is inserting the copied taxt as a line above the insertion point.