To get to the bottom of your problem, you may have to track down the
actual factory in Denmark where these were made, and find out if
they were cast, or drop stamped.
Here in the UK, flatware is invariably made from rolled annealed
sheet, blanked then drop stamped between 2 dies.
theres no faster or better way to get the detail than drop stamping.
You would never get the sort of weakness and or porosity you seem to
have in rolled amd stamped metal.
Also here in the UK, we are forbidden to remake any hall marked
sterling item into another product, without having it re marked.
which defeats the object in making bracelets from old sterling
However, Ive made many hundreds from EPNS, and never had a joint
break in this alloy, brake elsewhere, yes, in the bending round
Any chance of a picture of the joint design? In a cuff shape, ie open
"C" shape, theres little bending in the middle section where I
presume the joint is.
You will have parts of the spoons as experimental metal. anneal the
bowls, flatten, cut a couple of strips and solder together.
Then do a bend test. The joint and the strips should take being
folded back on themselves. If they break, then it is likely the metal
is not rolled and stamped, but cast.