Continuing on from the previous post.
I think I understand the solution, and partially understand the problem
The French translation is linked to the original English.
Those references allow us to hover over translated text, and see the original sentence displayed in the dialogue box.
When we copy the French translation, and paste it for reverse translation.....
..... we are not copying only the French text, we are also copying it's references to the original text.
AND apparently we end up sometimes copying the original text, rather than the translated text.
Therefore, we need to copy the translated text, like as if we had highlighted it........ and paste it, like as if we pasted a copied web page into a text editor.
Effectively a fresh start, without any references to other text.
That's the solution.
It seems logical, and obviously works when pasting the text in a Fr2En version of the sys.
The question is, how to do it?
I'll perhaps revisit the innerText/textContent elements.
Also I'll rebuild my sys that used onClick, to fully test AndrewGSW suggestion that by pausing the processing, we might be able to copy the displayed French every time.