The mission Xiao Lian got was actually something Lee had in mind. Their task was to go to a smaller sect in a remote region and pick up a delivery for the Mission Hall.
Lee's guess was that no one wanted to spend two months on the road, away from the sect's cultivation resources and, maybe, social life. He, on the other hand, was thrilled to have a personal teacher who dedicated his time to teach Lee how to read and write.
In a few days he became capable of freely understanding what exactly was written in the techniques they bought, and after a month he was pretty confident he could write down almost anything that came to mind.
Of course, the boys didn't neglect the training. Xiao Lian was slightly upset he could practice his fancy cultivation technique only during the morning and evening cultivation sessions, but until they were back in the sect, there was no way around it.