I don't own an i10, so I don't know how the latest i10's speed-limit warning system should function, nor what capability the owner has where the system settings are concerned.
This Australian article
"Turn it off!": This annoying Kia and Hyundai safety feature is enough to drive you spare! | Opinion
refers to the Hyundai Palisade model's 'over-speeding' reaction as
a flashing speed sign in the digital instrument cluster and four loud beeps, but doesn't say if those two warnings are simultaneous or cascaded. Logically, if the warnings are to be cascaded, there ought to be a delay between the visual warning and the acoustic warning that is sufficiently long for the driver to begin to slow down and for the system to recognise that action.
In principle the Hyundai system should be able to recognise and correctly interpret traffic signs that indicate an implicit speed limit. For example
where the UK speed limit is 70mph (for not-towing cars) for the first two signs and 60mph (for not-towing cars) for the 3rd sign. As I'm sure you realise, the speed limit on UK main roads, dual carriageways and motorways varies according to vehicle type, usage and weight
and I'm guessing that the camera-only system Hyundai fits to its smaller cars would (at best) only cope with the 30/60/70/70 speeds in the first line.
As you've suggested), if the system only recognised 'defined' speed-limit signs that showed 20, 30, 40 or 50mph, that should side-step the car-park issue.
The reality is that whoever is responsible for the i10's traffic sign recognition system may be able to address fairly easily its current inability to recognise (or react correctly) to the UK's national-speed-limit-applies traffic sign. But that's all they will do - provide a 'fix' - and the chances are minimal that the 'fix' will include improvements of the type suggested in these forum discussions.