"They do not understand the extension of the problem."

Translation: Eles não entendem a extensão do problema.

[rmacheshire]

I think the English should be "They do not understand the extent of the problem"

[DanielChui1]

Agree. Extent

[seglea]

Agreed - unless, which I doubt, the PT means that they understand the main part of the problem, but not some extra bit