TF&TWS episode 3 spoilers

Well just look at the timeline. After Civil War, Cap was a fugitive and didn't have any power to pardon anybody. Sharon was already a fugitive as well at this period and would have started her life of crime/hiding. Later, Cap and the others fought Thanos and then half the world disappeared. I assume government was in complete turmoil during that 5 period stint and it would be hard to a.) Find Sharon and b.) get pardons from a government which was in disarray. 

Falcon and Bucky certainly weren't pardoned during that 5 year span since they were both blipped away. It's only after they came back, and after they helped in the final battle against Thanos, that they were eventually pardoned. Sharon wasn't part of that battle and seems to have still been in hiding during that time. It would have been hard for Cap to get someone pardoned when that someone was hiding. Then after that, Cap went on his time traveling vacation.