our plumber correctly installed our wall mounted spouts over the centre of the basin ie water directed to the plug hole but make sure that the basin is mounted forward of the vanity and spout is shorter rather than longer as the water can spurt forward if turned on too hard by unsuspecting guests

Save big money on importing one from the UK and spend it on design to make the space work for you without the need for such an impractical solution. There are some cute, tiny wall mounted hand basins which would be a neater solution. https://www.reece.com.au/product/basins-c448/wall-mounted-basins-c452/axa-cento-mini-wall-basin-right-hand-with-fixing-1-9505814 If there is no other option here is another type of toilet/handwash product, but I don't think it looks any better than the Caromo design, although overcomes some of the impracticalities mentioned in the previous comments. https://www.reece.com.au/product/basins-c448/wall-mounted-basins-c452/roca-w-w-integrated-washbasin-white-5-star-9505427 Best of luck, Dr Retro of Dr Retro House Calls/Dr Retro Virtual Visits

There are all ways pros and cons. My husband doesn’t like wall taps as they can leek into wall, but hey all showers have wall taps. Yes you drip water behind sink with a wall tap as happens with an undermount sink. But the base of tap doesn’t get grimy like a sink mounted tap. With a wall tap you may need a long spout to get over sink, as you do with an undermount sink if you have a bench mounted tap behind the sink. So many choices. Buy what you love.

The need to seal it attracted my attention because, while I don't know about that particular sealant and things might have improved, the issue of surfaces needing regular sealing is not very sustainably eco friendly and can have health implications. Do you know what solvent/s the sealant contains and what precautions are advised? The other question that comes to mind in relation to your actual question is, how vulnerable might the surface be as it's coming up to the time for resealing?