Actually, unmasking has nothing to do with the FISA courts. When the NSA records foreign conversations, it is because they are allowed to record them. The names of Americans are automatically redacted from the NSA's records unless a unmasking is requested from someone authorized to do so. Samantha Power asked for the most redactions (she was Ambassador to the UN at the time). One may justify her asking for the redactions (I do not) as she was negotiating with Russia and all other nations at the time and the call involved the Russian Ambassador. The real question is why the others asked to see the unmaskings. To understand better, read the transcripts of the call or the summary and ask why anyone who need to take the extreme step of unmasking the American caller. We know the only relevant portion was when Flynn asked the Russian Ambassador to consider waiting before responding to the sanctions Obama had put on Russia. Heck, all kinds of American businesses had asked them to do the same at the time.