> Just say what you mean

This greatly depends on work culture and ARL's - adulthood readiness levels.

Many people are not graceful with open criticism even if done privately and constructively.

Without falling into stereotypes culture still matters specially in an international setting. Some cultures expect a lot of innuendo and indirection, for example in British or Japanese work environments. West coast US typically expects a lot of positive praise even when pointing out negatives. Whereas others like the Dutch expect more direct or even literal speech.