I think I have discovered that the IKEA hobs are only supplied with jets for propane/ piped natural gas.
So it looks like changing the jets is the way onwards. The hob allows for the power to be adjusted but not the burn mixture.
As for rules..well yes there are probably rules, but France being France nods their head and then goes and does what they want. I think i can handle this, after all it’s only a glorified cooking stove with an infinite supply of bottled fuel. I change the jets on my multi-stove msr stove. Not sure insurance companies work like those in the UK either in case of a fire.
I deem myself competent to service my bicylces that I ride down steep alpine passes…and my childrens. I’ve also re-wired said kitchen without getting it signed off. Vive la france!