I do have a function to do fightin words term ranking, and the funnel plots as well, although the code is a bit messy. I am attaching a tech report I wrote about this that includes some example funnel plots. Happy to try and collaborate to add this to quanteda.
The term ranking operates off of a contingency table (just aggregated term counts to category level) which I represent as a slam::simple_triplet_matrix objects (I always found these more intuitive to program with).
From @matthewjdenny (Thanks Matt!)