I think you might need an Italian electrician.
The word 'shunt' I believe means provide with electricity, by linking together.
In the UK the generators have a 3 phase output which is only used by commercial firms,so they would have cables with 3 live wires and 1 neutral.
The distribution to houses would use only 1 of the 3 phases plus a neutral for all roads, but three adjacent roads may all have a different phase.known as single phase.
I'm guessing a bit here but I don't think phase means the same.
Reading the remainder If terminals 1,2 & 3 were linked (shunted) and terminals 4 & 5 were also linked, you would effecively have only two terminals and if neutral went to 4/5 it would leave live going to 1/2/3.and that to me seems to comply.
What I would do before you think of wiring it , is to link the terminals as suggested and with switches in off position use a continuity meter across the two terminal groups, to ensure there is no path for electric.
Then seperately turn each control knob on and then off, proving there is a path. In addition it shouldn't be too difficult to trace where the wires go ,
after all, each single element only has two connections, although some hobs have a element within a element.
Let's see what Breezer makes of it!
He's beat to it I see