I don't deal with this kind of job too much but sometimes I have to migrate data from one system to another one. The cleaning is hard and specific to the data but most of the time I was able to deal with it using Regex find and replace and some command-line tools. For mapping, I would take 10 lines out of the CSV for test import, use AI or manually map the fields and then do batch import once the mapping is correct. AI can also help you clean, transform the data but the output may not be consistent.