Both Haskell and Prolog seem to run on a school-year cycle where search interest peaks a little before the end of the semester. Prolog's cycle is significantly more pronounced, suggesting the interest is indeed purely academic. Whereas Rust has been growing steadily and shows little seasonality.
I'd say it's random chance, given X million programmers and Y million articles there's always somebody who will see a lot of Z topic.
Terminus in particular seems to be an extension of work Gavin did during his postdoc, in particular the Dacura stuff mentioned here: http://aligned-project.eu/open-source-tools/. He deleted the DQS repository for some reason but there's a mirror here: https://github.com/bozicb/dacura-1.