Hi Beethoven,
I am just finishing ATPL exams and was also unsure about how the various extensions applied to me. I emailed FCL exams and said something along the lines of “I understand extension X means that I have until date Y to complete my exams. Please confirm this is correct”. They replied confirming, so I knew exactly where I stood and had it in writing straight from the horse’s mouth.
I hope that helps and good luck with the exams.