Is this just giving a general-purpose agent a workspace full of documents and an assignment, then seeing what happens? I feel this doesn't really say anything. It appears they mostly dumped all of this in base models with little to nothing in the way of infrastructure to support it. If you just randomly grab some person off the street and say 'do taxes' they would probably mess up just as badly. The interesting question would be what the models could do in a well engineered harness focused on taxes. That would be reflective of the performance boundary and how serious we would have to take AI in that field.
How do you think 99.95% of people who do taxes with gen AI are doing it?