1. Always use good quality and new (check packaging date and expiry) yeast. If the yeast is old, it will not froth as it should and there is no point baking your bread with it. It is better to discard and start again. If however despite this your yeast does not froth or you are living in cold weather/central AC try placing the bowl of the yeast mixture in a larger bowl of hot water. I noticed that it will help the lukewarm water in which the yeast has been dissolved to maintain its temperature and aid the frothing. You can also add 1/2 teaspoon honey to the mixture when you make the Cresiuta as it will aid the frothing.
2. I always like to use instant yeast which is similar to active dried yeast but has finer granules and need not be dissolved in water, yet I did that for better results.
3. Since I didn't find readymade semolina flour I bought the finest semolina I could find (sooji rawa) and ground it to a fine texture in the dry grinding jar of my mixie. If you are following this method make sure not to overload your mixie jar - fill it upto half its capacity and grind the semolina for best results. 2 cups of sooji rawa will yield you approx 2-1/4 cups of semolina flour as the volume increases once ground. You will need just about this amount, but if you feel that the dough is still sticky/gooey (sticks like paste to your hand) then grind some extra semolina and dust the flour. The dough is supposed to be soft and slightly sticky (but not paste like)