A couple of very important things you are not understanding in your exuberance for a gotcha moment.
First of all, what you are missing is these warrants aren't approved by the FBI. The application is done by the FBI. The warrants aren't approved by the FBI. Just because the FBI applies for a warrant, that doesn't mean it is granted....and this was thoroughly explained to me by my FBI buddy who is also a republican that you are aware of. FISA court has to approve it and this is a rigorous approval process that makes a typical warrant approval process look like chopped liver. This is done by judges of all political backgrounds. People who go on facts alone.
I saw you mention in a post last week fruit of the poisonous tree. Well, i am aware of what that is...and that isn't this here. Because a judge already approved the warrants. This isn't like the OJ case where because the cop was crooked, all the evidence gets thrown out by a judge. No, this is actually the judge already approving the warrant...lol. So it isn't fruit from the poisonous tree if a judge approved it.
Then a judge has to review it and based on the information provided or not provided it is approved again or denied. If there were nothing there, then it would be denied. It was continued because there was something there.
Now, in regards to Comey and Trump there is a process upon which this can be properly litigated. That isn't in the public forum. This is a matter for Trumps attorneys if there is any merit to it.