I also write a lot about things I learn and not always fully understand yet. My secret worry is that one of my readers will meet me in person and quiz me verbally on the subjects of one of my articles. I would end up sounding really dumb compared to the impression made by the article!

When it comes to pretending to know something about things you don't understand, I think there's a big difference between talking and writing. Talking is bad because you're not equipped to form intelligent off-the-cuff sentences about the thing. But writing can be okay, if done with care.

Some things I would be able to talk about because I have insense opinions enough to remember (e.g. insurance purchasing decision logic), or they are easy to remember (the alpha-max plus beta-min algorithm), or I wrote about them recently enough to remember (how to perform an FFT). But ask me about anything else (sloppy confidence intervals for Pearson correlations?) and I'd just stand there.