The dangers of down lights covered by insulation is an unknown or ignored issue. Too many 1990's era house ceilings that I have inspect recently have had insulation over or covering the halogen down lights.
This is a fire risk due to the temperature build up around the lights. There should be a clearance of 200mm to any combustible surface and 50mm clearance from the insulation bat or transformer.
Down light barriers or domes should be fitted to ensure compliance especially if loose insulation has been used.
Alternatively have an electrician replace the lighting with energy efficient LED down lights. LED lighting generates less heat and alleviates most of the heat build up issues.