The phrase "pivotal question" is correct and usable in written English. It is used to describe an important question that is essential for understanding a particular subject or situation. For example, "What will be the impact of the new policy on the economy is a pivotal question that must be explored in greater depth.".
It is a pivotal question in the evolving world of white-collar work.
For Kerr, the pivotal question remains precisely who the eel are being sold to.
A pivotal question: what kinds of decisions should be made on the basis of belief rather than reason?
The level of animosity that a Clinton candidacy could arouse is a pivotal question in the 2008 campaign.
But the models have not clearly answered a pivotal question: how sensitive is the climate to the intensifying greenhouse effect?
Again, the pivotal question centered on Pakistan's army: Just how hard was it really trying to capture and kill terrorists?
Another "pivotal question," he said, "is the value of the health care business on a stand-alone basis".
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com