Is a damaged wall that is struck guaranteed, despite doubt regarding the occurrence of the damage?

We advise you to stay away from obsessive whispering (waswasah) and to completely disregard it. The default state for a wall is the clearance of liability (bara'at al-dhimmah), so there is no weight given to doubt, because the default is the clearance of liability. Allah created His servants with their liabilities and bodies clear of obligations until the reasons for their necessity are fulfilled.