According to the UG, there is no description that implies that the date cannot be in the past. However, when attempted to use the function to add a task in the past, it was rejected by the application.
e.g. add apple /do 25/3/2022 /start 23:18 /end 23:19
add apple /do 25/3/2022 /start 23:18 /end 23:19