That's a really nice project indeed. We looked at it I remember, when we pciked jOOQ, but it was too new to bet the farm on back then. It progressed really nicely.
Building on top of IntelliJ's parser and 'PSI' stack as a headless engine sounds slightly mad at first but seems to provide a lot of leverage, as demonstrated by the number of dialects the team is able to support via mixins. By contrast sqlc appears to require a lot of code to support each additional dialect.