I don't know anything about this test, its answers, the site quoted or Google Translate, but a sentence saying _X deve accertarsi se Y_ undoubtedly means "X must ascertain whether it is the case that Y (or not)". See for instance part 2. of http://www.treccani.it/vocabolario/se2/ ; you'll that in none of the described uses, even when the context is ironic or emphatic, _se_ can be substituted with _che_.