I found a reference to your specific inquiry in the Aug 2018 issue of Practical Sailor (https://www.practical-sailor.com/iss...y_12456-1.html
Without personal experience with either a Beneteau, nor any boat built to CE certification, I have no idea if your Beneteau truly has a CE certification, or is simply "...built in accordance with CE standards" as the above reference states. Therefore, I can't state with certainty what the materials Beneteau uses in it's seacocks.
Having said that, and after attending a Beneteau boat show presentation that had several seacocks on display, I believe that HopCar is correct-the basic material of your seacocks is brass, vs bronze. The Beneteau seacocks are, however, nickel plated, for whatever that's worth.
So, your concerns are justified. However, perhaps not to the point of rushing out and replacing all your thru-hulls "just because". The Beneteau response above also correctly suggests that thru-hull failure is more likely due to poor maintenance and corrosion control than it is materials.
For what it's worth, I would suggest careful inspection and maintenance of your existing thru-hulls at your next haulout, and proceed from there. I would further suggest that with adequate care, your existing thru-hulls should lead a long and happy life.