I have previously approached similar projects by using unsupervised learning using K-means clustering. That would be a pretty cool experiment and maybe the algorithm even comes up with a better categorization 
You can read about such an approach here Applying Machine Learning to classify an unsupervised text document | by vishabh goel | Towards Data Science
Just like @EricGT said: don’t be afraid to iterate, but close enough is close enough, and maybe have some TL3 users ready to re-categorize where necessary.