Pashuteh Yid-
Those are valid concerns, and you’re correct in being machshiv yenem’s feelings.
However…
1) If you or someone else points out these “needs improvement” areas as tactfully as possible, would the person overcome their hurt feelings and ultimately benefit greatly from your intervention?
2) How would you want to be treated if the situation were reversed? Personally, I’d want to be told.
3) The only circumstances that not telling should be an option is if you know the person wouldn’t heed the advice and/or would become enraged at the advisor (not just short term hurt feelings).