I doubt that. Yesterday's Enterprise was pretty clear: the Federation and Klingons fought a twenty year war and the Federation lost. What more do you need?
The Federation did NOT lose the war.
Picard only said to Garret (in a very low voice no less AFTER she explained her desire to NOT go back through the rift) that the Federation was losing the conflict.
We don't know if this was actually the case, because he could have simply said so to encourage her to go back and prevent the war from ever taking place.
Granted, it's likely both the Klingons and Feds sustained heavy losses, but either way, I doubt the Feds would suddenly lose after 20 years of sustained conflict (and Picard would probably JUMP at the chance to undo the war and prevent numerous losses on both ends).
Furthermore, the war itself in fact doesn't make sense after ST VI.
It was also mentioned in the movie itself that SF back in Kirk's day would be able to beat the Klingons. Of course, this could have been nothing more than SF commander touting his best to the President, but even so, I never got the impression that SF would be incompetent back in that time period.
Furthermore, if the Klingons decided to go to war over 1 conflict where the Enterprise-C looked like as if it fled the battle, then they have some serious issues.
Where were their own ships to defend Khitomer?
The 'excuse' was a poor one at best. But either way, in YE timeline, we don't know if the Federation actually lost the war or not.