The phrase 'how significant a role' is correct and usable in written English.
You can use it when you want to emphasize the importance of something, for example: "John played an important role in the success of the project, but how significant a role he had is something we shall never know."
And how significant a role did your heritage play in your new lives in Germany and the United States?
Most important, "The Youngs" gives a full portrait of just how significant a role George Young, Malcolm and Angus's older brother, played in AC/DC's development.
This must be followed quickly by a decision on how significant a role the party itself will play during the campaign.
More recent research indicates some relationship of sleep bruxism to neurochemicals like dopamine, but there is still disagreement on how significant a role they play.
Part 1: If the 49ers are to win the Super Bowl, how significant a role must their defensive line play for that to happen?
But this is starting to change, and Oforiatta-Ayim says the exhibition, scheduled to be held at ANO, a new art space in Accra, in early 2017, will showcase just how significant a role Joe has played in Ghanaian culture.
2 36pm: How significant of a role do you see M&A in terms of the strategy?
Marketers must embrace just how significant of a role social networks play in people's lives and embrace these new social norms.
Though the courts found Mr. Afzal to be complicit in the attack on Parliament, it remains unclear just how significant his role in the plot was.
Huang's main link to the NBA was to help link up a top Chinese player to the Cavaliers and he was also described yesterday as an "ex-exclusive Chinese marketing partner of the NBA Cleveland Cavaliers", though precisely how significant that role was remains unclear.
