I would argue Oda failed at this too.
We have actual internal dialogue from Orochi saying he doesn't know whether the scabbards have returned or not. Like he can't be lying to anyone when he says thus since he's just saying it to himself
Orochi says this AFTER reviewing the Intel from Kanjuro. Why does he say he doesn't have proof of the scabbards returning when one of his men is a Scabbard?
I will say this again... spoiler isn't the most accurate when it comes to translations... so wait until official release...
Secondly.... while EVERYONE in Wano called Orochi a coward... and that he's just scared of ghosts... he was hell bent on believing Kanjuro's words... he even said in one of the panels... "it's hard to believe that they time traveled" So the info of Kanjuro and Kinemon and co traveling through time was so shocking to him... that even though he trusts Kanjuro.. he just felt it's hard to believe...
And I will repeat again... you guys need to chill until the official translations... because sometimes small changes in the lines and quote can make his tone and words "sound different"
Orochi on MULTIPLE occasions through this arc says "who cares if everyone doesn't believe if the scabbard returned or not.. as long as I know it.. and I'm in power" he fucking said that.
Go back and re-check the chapter that came right before the flashback... were Orochi was ruining their plans and destroying ports and bridges.. Orochi is so focused and wholeheartedly believes they are back...
However, I also want you to think for a second about Orochi himself... although he believed in Toki's words... he had NO CLUE where did Kanjuro disappear for 20 years. And then Kanjuro showed up after 20 years... and e reports to Orochi what happened... Wouldn't you think Orochi is justified to have "shock" and question what happened 20 years ago!???
Sure, he's your spy... but at the same time... there was 20 years gap between Kanjuro's last report and now in present! 20 freaking years passed and then suddenly you receive a letter message telling you that the scabbards are back.... so of course you will have some doubts and conflicted feelings!
However... throughout all of this arc... orochi proved to be a great character by taking those letters seriously and believing that it came from his own spy... and taking precautions against them until he was more than convinced they are back.
But then again... I will repeat what I said... translations in spoilers are known for their mistakes.. so wait for official ones