I don't see why you shouldn't connect the oven power input L1 and L2 together to one side of your 220v supply, and L3 to the other side of your 220v supply. Hopefully you have the ground connection available.
I don't think the inverter is necessary for this. The elements and transformer all appear to be 220v.
However the current draw will be approx 40 Amps, so suitable supply, cable, connector and breaker(s) needed.
I'm assuming it really is completely wired as per the diagram!
And to emphasise you would be entirely responsible for the safety of the thing having connected it differently from the manufacturers instructions. But based on the circuit diagram (unless I've missed something) this seems a possible solution.
Comments please.
And as above, sorry to have missed the original post a month ago!