The appliance that I was referring to was made by/for a large, reputable, European HQ'd manufacturer whose brands account for a good fraction of mid to high-end UK appliance sales. My observation was specifically that it seems more likely that the literature and specification is in error, at least in the English version, than the design of the appliance.
My reasoning is that the error appears to be of a form that often occurs when different versions of a product are marketed to different territories with different versions of instructions. Sections that need to be replaced altogether to account for version differences are sometimes translated instead. Here, I suspect that the difference between the maximum power input permitted in the UK and German versions has been overlooked when compiling the English instructions.
E.g. where a German manual instructs the user to connect the appliance to a 16A Schuko socket, the English might say 'Connect the appliance to a 16A safety contact'. The incorrect wording 'safety contact' is a clue that a section of text that should have been replaced outright with 'Connect the appliance to a 13A socket-outlet' has instead been translated, therefore the reference to 16A might also be a mistake. Just as I routinely find instructions for US-made, CE-marked, 230V-compatible gear sold in the UK to use only a UL-listed cordset to connect it to my 120V grounded receptacle.
In summary, I do not think it was the intention of Bosch to imply that a 3.7kW load may be supplied via a 13A plug, and therefore to flag it as bad design and blame such a practice for damage and failure would require verification as to whether that really was their intention. If so, then I agree fully that it is bad design.