Hi Jomaco,
No it’s not true at all. You can read more about the different types and blends of latex in post #6 here that can help you compare them regardless of where they are manufactured.
Sri Lanka has several manufacturers that make high quality 100% natural Dunlop latex including Latex Green and Arpico and I would have no concerns at all about the the quality or durability of either the Dunlop or Talalay latex that Flexus is using.
A component mattress with loose layers that has a cover that can be unzipped allows you to fine tune the mattress after a purchase by either rearranging layers or exchanging a layer. There is more about the pros and cons of both of them in post #2 here and the posts it links to.
Phoenix