Well, there are trade-offs being a reporter. Haberman is given access others don't get and in getting that access there are likely many things she learns and does not report, either because she is asked not to report them, they are given only as background, or yeah, maybe she saved some juicy bits for her book. 

I am guessing there were reasons it was not reported, maybe she got that info unrelated to the work she was doing for the Times. Can't really say but Trump did so many illegal and morally and ethically outrageous things, maybe taking $20 million to move the embassy was just seen as something that did not need to make it into a Times article. The other thing is, yeah, he took the $10 million from Egypt in a bribe to release military aid to them and Barr shut anybody looking into that down, perhaps the same would have happened with Trump taking the $20 million from Israel to move the embassy. Essentially, it would seem the way they needed to prove these things was to get access to Trump's bank accounts to show the money going in and Barr prevented and would not authorize doing that. The way he responded to the $10 million bribe from Egypt seemed to indicate Barr knew Trump was taking these bribes and was not going to allow any investigation to expose him. 

This is how Trump pretty much openly plans to conduct foreign relations, everything is for sale to the highest bidder. Yes, it is a betrayal of the United States, it is totally corrupt, but he is pretty much openly corrupt and got away with it in his only term as president, and now can get away with it with absolute immunity. I do wonder how taking bribes and depositing the money in your personal accounts could be seen as an "official act" but if killing political rivals can be seen as "official" a bribe sure as hell could.