How strong is construction of this catamaran in storm?

IMHO, all multi-hulls will suffer in high seas with the significant threat of turning turtle. High waves/winds striking the underside will find a huge sail area to catch. Seen too many tragic results where a monohull would have been fine.

I agree with Luckylg, usually Cats and Tris have more rig failures because they have more sails than a monohull; especially their mainsails exert a lot of pressure on the mast.

There was a record attempt by Groupama 3 to beat Orange II, however the boat capsized 80 miles off New Zealand. The trimaran's port float broke down on impact. The risk with Trimarans is the high loads exerted on downhill surfing where the boat goes bow-in on the port or starboard side.

On heavy weather (10-12 meters) however not even a monohull would survive a breaking wave on its beam, but it will right itself if the sails are reefed enough. Downwave control is diminished by wider beam and lighter displacement of many serial production boats, furling sails increase the risk as there is more weight above the water. The boat in the pictures has a wide beam, they would have to plan ahead in terms of bad weather avoidance imho.