No grey area.
The BRE have carried out research which indicates that downlighters have no significant effect on the nominal fire barrier rating of plasterboard. But, in any case, it is only compartment boundaries that have a fire rating and in a single dwelling only an integral garage ceiling with a habitable room above is classed as such a boundary.
I saw your post about your 2391 and was tempted to reply. Your tutors are correctly concerned with BS7671 regulation 527-02, but are ignoring the bit that says, "...according to the degree of fire resistance of the element concerned (if any)." That necessity is not defined in BS7671, but in the Building Regulations.
To rate a domestic installation as 'unsatisfactory' because the kitchen downlights were not 'hooded' would be totally incorrect.
That said, of course, many building inspectors seem to have made up their own regulations as well, so it is wise if installing to check what your LABC has to say about it. And at the end of it all, downlights with integral fire/acoustic containment properties are never going to be a bad idea.