Final answer:
The critical grammar topic in the passage is semantics, which deals with the meaning and interpretation of words in context.
Step-by-step explanation:
In the passage provided, the grammar topic that is critical is semantics. Semantics refers to the meaning of words and phrases in a particular context, and it is clearly illustrated by Nancy McKinstry's adjustment in her language when communicating her strategic plan. By changing the descriptor from 'aggressive' to 'decisive', McKinstry was able to communicate her intentions in a way that was more palatable to the European audience she was addressing. Understanding the connotations and cultural sensibilities attached to words is a key aspect of semantics.