It is not the same thing to see that the traditional Chinese character "samarium" is "samarium" and the traditional Chinese character "tin" is "tin".
Not only Xu Xicheng, but also most people in society think that "tin" and "samarium" are the same word.
From another point of view, the word "Lu" is an uncommon word, which is easy to cause misunderstanding.
Even so, it can't be concluded that Xu Xicheng's calligraphy level and knowledge are low. Maybe he was careless in Jingzhou and capsized in the gutter.