The quality of calligraphy works should not be judged by whether they have been altered or not. Because people are not machines, it is difficult to be accurate. The world's earliest running script "Preface to Lanting Collection" is also smeared. But there should not be many typos. Since he is a well-known calligrapher, he should not write many other words. The other words you say may be variant characters or traditional characters. Those that belong to the research category of calligraphy art should not be regarded as other characters.