Here at DaniWeb, we use a combination of a forum structure for top-level categories (web development, digital marketing, etc.), as well as a tags to denote specific technologies (php, etc.).
For many years, the moderation team wasn't actively doing a decent job moderating tags, and we now have a lot of older forum topics with incorrect tags, irrelevant tags, etc.
I would like to use AI where, given the list of available tags (it's a relatively finite list), it will properly tag all ~400,000 topics. As of right now, the only language I'm very comfortable with is PHP, because it's the only language I've coded in for the past 20 years.
What is the least expensive way to take on this task?