Certain things cannot be mentioned. Yet, everything can be meant. It's not impossible to convey any feedback. One just needs to figure out the best possible way which leads to change as well as less offence. And, if one has to prioritize between change and offence, change shall be prioritised if time is running out and offence shall be avoided if there is sufficient time left. So like many a things, the art of conveying is also like a "trade off" that demands loads of maturity and clarity of thought. Not everyone can master this. Not everyone can sustain this. It's easier said than done, indeed. Still, a lot worthwhile to practice.