What do you mean by “taxonomy”? Assuming you’re using DU, the taxonomy is just the collection of documents and fields you define, it doesn’t replace anything.
Do you mean the output from the Digitize activity is wrong? This is usually an OCR error, a capital “I” being replaced with a “1” and vice-versa is a pretty typical problem. How to deal with it depends on what you want to do with the data - if it always starts with 4 letters, replacing any “1” in the first 4 letters with an “I” might make sense. You can get similar issues with “0” (zero) and “O” (capital letter o), “8” and “B”, and “5” and “S” depending on the font and quality