I am going to make a 3 tiers cake for a friend, she is form Puerto Rico, and i would like to surprise her with moist cake like they do it in her country. My question is, Can i used the simple syrup to moist the cake, without risking the cake to collapse?
It might depend on the cake recipe you mean, I'm not familiar with Puerto Rican cakes.
Your cake would have to be pretty soggy to collapse.
the cake will be a regular yellow cake mix
I learned about the simple syrup trick and have been using it ever since. Also after you cool the cake, wrap it in plastic and freeze them. For some reason, that seems to help the cake maintain moisture.