The heater exchange mods are only valid for a set of unrepresentative tests.
The tests themselves raised supposedly previously unknown behaviour of fuel/water mixtures (?????).
SO;
1: They still need to carry out representative tests (of whatever sort) which cause the engine problems or otherwise explain the engine failures by suggesting different fuel conditions from those extrapolated from the evidence.
2: IF there is this previously unknown behaviour of fuel/water mixtures then ALL - REPEAT ALL - certification authorities and ALL - REPEAT ALL - airframe/engine combinations need to be re-checked to see if they are immune from these effects.
Strangely enough it is the second of the above that I have more problems with. I await the final (or third interim) report with interest.