I think it unlikely that heating coil current could induce permanent magnetism into the Ni ash in a Rossi type system. Firstly because he is known to use square-wave polyphase AC to run the heater coils (see Lugano paper page 6) and secondly because of the Ni was above its Curie temperature (327C) whem a potentially magnetising coils is switched off, it will not be magnetic when cool.
It is not true that the fuel necessarily reached Curie temperature. Remember that my samples are from the classical E-Cat which was water cooled.
The ash is marked 12-1-'10--2-15-'11. I do not think we know what shape Rossi used for that run.