I accidentally discovered that CUPS has a web UI at http://localhost:631/printers/ (in my case) that has more options than the Ubuntu system widget has and is just less cramped. Most notably, the jobs queue is easier to read.
I still don't know why Chromium can't successfully send jobs to CUPS, though. (And probably Firefox, though the only things I try to print directly from the browser are Google Sheets, which I use in Chromium so I don't have to stay signed into Google on any Firefox profiles.) So, I always end up saving to PDF, then printing that.
Printing: It will never become easy.