The title is correct. You are looking at average temperature rise. The article states by up to which is the maximum temperature rise.
If you catch me on fire my average temperature rise doesn't go up very much, but I have the barest of hints that it might have an impact.
Never said anything about correctness.
No it's not correct, because no causal relationship has been established between the data center and the most extreme difference measured.
I understand that the study only showed that this was the maximum observed difference downwind of one data center during one run.