Are reden (to talk) and plaudern (to chat) completely interchangeable?
I was told that plaudern might sound intimidating in certain situations--is that true?
I would never use plaudern.
If someone else uses it, 99% of the time it's a native English speaker who thinks it's a common word in German.
It is not, in my experience.
If I want to chat with someone, I would use reden ("talk") or sich unterhalten ("converse, have a conversation").
I wouldn't call plaudern "intimidating" so much as "very uncommon, possibly unnatural".