Even plain wood does produce small amounts of formaldehyde naturally. Natural wood emits less than urea formaldehyde and phenyl formaldehyde glues, it’s true, but still some. Given that this research seems aimed at reducing the formation of formaldehyde in the wood itself, and glues/binders typically already have formaldehyde in them and no chemical process is needed to produce it, I am guessing they really are referring to the naturally occurring formaldehyde that is emitted from the wood itself. Which would not be covering up nasty pressed board but instead increasing air quality even in a no-added-formaldehyde construction.