Does sin befall one who completed their 'Umrah despite doubting the number of circuits, knowing that they are frequently doubtful in acts of worship?

The basic principle is that whoever doubts the number of circuits during circumambulation (Tawaf) should base it on the lesser number. However, some verified scholars, like Ibn Taymiyyah and Ibn Uthaymeen, preferred the view that if one's predominant thought leans towards something, then they should act upon it. They also stated that this was the madhhab (school of thought) of Ali and Ibn Mas'ud, and it applies to Tawaf, Sa'i (the ritual of traversing between Safa and Marwa), and Rami al-Jamarat (stoning the pillars). Therefore, the questioner's Tawaf is valid due to the predominance of his thought regarding its correctness and the frequency of his doubt.