diffused across a ductile Pd metal which isn't involved by embrittlement under hydrogen
Please don't be too concerned over the use of the word "embrittlement". Even HE researchers freely admit that it is a misnomer, as there are examples of increased ductility within the crack region, with possible increased mobility of dislocations. The term is a hangover from the 19th century - and really needs to be abandoned in favour of "hydrogen induced failure", or some such.
I started to suspect LENR involvement in the observed HE effects some thirty years ago - but to suggest that within the normal HE research circles was (and still is) "forbidden"