Run a simple test. Take the new writer and put them back on the monthly doc for two months. Results should tell you fast. Usually it's the person, not the process. Calendars don't write good headlines. Freelancers do. My money's on the writer.

Is your tablet's pressure curve set to a softer sensitivity than what you're used to? I had the same panic once, then realized the driver reset had boosted the curve and I was pressing way harder than normal to get the same line weight. Might be worth checking your settings before blaming the nib itself.

Swear to god, rusty water on a control panel is my nightmare, and you mopped it up in 2 hours? That's impressive, but your Z axis acting up now has me worried it got into the encoder or something.