It is not clear if by "Comey corroborated" you mean (according to McCabe's testimony) Comey approved of the leaking after the fact, or if you're saying Comey corroborated McCabe's testimony. If you mean the former, that's true, but not the later.
(I apologize in advance if you meant the former, and thus I'm basically arguing against something you weren't trying to say)
In my prior post I linked
to the report of the Office of Inspector General which was very harsh on McCabe's conduct. In its summary on pages 22-23, it says the following regarding the conflicting reports:
We concluded that McCabe lacked candor during his conversation with then-Director Comey on or about October 31, 2016, when they discussed the October 30 WSJ article. As detailed above, Comey and McCabe gave starkly conflicting accounts of this conversation. Comey said that McCabe “definitely” did not tell Comey that he had authorized the disclosure about the PADAG call. To the contrary, Comey told the OIG that, on or about October 31, McCabe led him to believe “in form or fashion” that McCabe did not authorize the disclosure about the PADAG call to the WSJ. Comey described how McCabe gave Comey the impression that McCabe had not authorized the disclosure about the PADAG call, was not involved in the disclosure, and did not know how it happened. By contrast, McCabe asserted that he explicitly told Comey during that conversation that he authorized the disclosure and that Comey agreed it was a “good” idea.
While the only direct evidence regarding this McCabe-Comey conversation were the recollections of the two participants, there is considerable circumstantial evidence and we concluded that the overwhelming weight of that evidence supported Comey’s version of the conversation. Indeed, none of the circumstantial evidence provided support for McCabe’s account of the discussion; rather, we found that much of the available evidence undercut McCabe’s claim.
So Comey didn't corroborate McCabe's claim that he told Comey. Though, as you say (and as I noted in my prior post) McCabe did
not claim that Comey authorized him to leak it, just that he told Comey about it after the fact (as is stated in the above excerpt, though it's more clear in its more in-depth description of it earlier on page 12). Their disagreement was on whether McCabe told Comey about it afterwards.