I had a flat roof on a townhome in San Diego and it developed a leak where water pooled. However, SoCal seems to be in permadrought and it is likely you would never experience enough rain to cause a problem. I'd simply get the roof checked every autumn.
I would be more concerned about the extent of the rehab. If the place was truly gut rehabbed, complete with new wiring, plumbing, insulation, underfloor, and exterior cladding in addition to cool floors, fixtures, and walls then it will be fine. If it was a cosmetic reno, stay away. Not sure about Hollywood, but similar areas of San Diego were plagued with flips and condo conversions that looked amazing but preserved old infrastructure.