Total Credit Delta is only used for the calculation of how much the network owes you. You are then rewarded the sum total of all the GRC for everything you've researched (up to a six month period) in one stake.

So in your example, the network will see that you have a high TCD after completing your GFN22 workunit and it will add the appropriate amount of GRC to the amount your will be rewarded in your next successful stake. Then your TCD plummets and it adds much less to the already existing pending reward. Finally you stake and you receive it all.

TL;DR: Yes, your reward carries over even if you don't stake. You will still be paid fairly.