I only have experience of Cat C & B boats, and I have reached the conclusion the CE marking is a sales aid only for distribution of boats in Europe. It is not a code for the quality, or integrity of construction of the hull.
I was lead to believe that a cat B hull would, by its rating, be stronger, harder, extra layup, stronger internals etc and more seaworthy than a C, and to some extent they are, in that it is a bigger boat,.. but that is where it ends.
If its a poorly constructed bigger boat as I found to my cost with an 8.5 Northcraft cat "B", you can forget placing any credence on its cat rating. To be fair, part of this crafts problem was that the manufacturer plated the transom to carry horsepower it couldnt handle.
But also, and this is important ..because of the weight distribution and layout of that boat, it was far too bow light, and to be honest taking a sea head on in a big six or seven was a challenge, so .. as to your question of seaworthyness, even supposing it was a top spec boat coded for B, if it aint balanced, or fitted in such a way as maintain good seakeeping, you can forget the cat system as having any real importance.
Ah just seen your other thread and posts