I don't think there are 'universal' mispronunciation issues. There are some very 'jw' words that you rarely hear anyone else use. When you hear one it just makes you tense up!
Words like 'materialism' 'pioneer' 'worldly' 'headship' 'paradise' ugggh! It's funny how I heard these words a gazillion times a week for 24ish years of my life and now I can go YEARS and never here them in a normal conversation. Of course when you DO hear someone say one of these words it's like a freakin' ice cicle down your back isn't it!
We did have some people who pronounced things HORRIBLY though. One woman in my old hall always said 'leapers' instead of 'lepers.' One older brother whenever he was reading and came to a word he couldn't pronounce always just said 'wheelbarrow!' As in "David turned to his son... Wheelbarrow, and said all this land will belong to you one day is the utterance of Jehovah just as I promised moses when he was fighting the... Wheelbarrow's..." Etc. It was a real hoot
The scary thing is he was a MS working toward elder I'm sure that he's right now conciling someone on their life their relationships and their future... Scary!