1) If we have the 'wrong' subject that does not tally with the perfect as a time period leading up to the present, then we have 'problems'.
I suppose so, but native speakers don't choose the wrong subject. If they do, through ignorance of the facts, then the listener will pick this up with some comment such as 'Didn't you know that Churchill was dead?'
2) If we have the 'right' subject that does tally with the perfect as a time period leading up to the present, then everything is Okay.
Therefore, it depends on the subject whether or not we can interpret the perfect as a time period leading up to the present, but if the subject does not allow us to interpret it so - see 1).
If we don't know the subject well enough to use the appropriate verb form, then we probably won't be speaking about him/her.