For those who don't already know, a partial translation of the file is here:
http://www.dctp.ws/Latest/Spoilers/V80-11Read/A1.html
And now I'm going to paste what I said in the spoiler cbox here, and add some stuff (okay, this ended up being a TON of stuff) I left out to save space:
I'm not totally convinced that guy is Bourbon. Mainly for the reason that he was in the bank as Scar Akai, and he knows what happened. So he should also know that the people without companions were the ones told to tape people up. If he were going to pick a disguise, knowing this he wouldn't claim to be the wife of someone who was supposed to be alone. The guy probably isn't Vermouth, since she wouldn't have to fake a cold and have a suspicious husky voice. This really only leaves Akai. It explains why the guy barely reacted when she mentioned the attack. Yeah, he asked about it, but it's a pretty half-hearted reaction to hearing about an attack from some mysterious organization. It would also explain how he knew about Akai dropping the can, but it's not really known whether Jodie mentioned it or just thought about it. If she did mention it though, it adds to his half-hearted reaction about the attack. Some mysterious attack would be much more interesting to comment on than a guy dropping his can of coffee.
Plus, when he drops the coffee, Jodie makes a
comment about how tired he is, which is something only Akai, Jodie and Conan would know about. Why would the man automatically assume that Akai was tired? Why not clumsy?
Also, I think it's likely that Bourbon isn't actually walking around as Scar Akai anymore. It wouldn't have been around anyone that he could get a reaction from, and it's not like he'd rely on some random guy telling Jodie that he saw him. Plus, he's already run into everyone that he could get a reaction from anyway, as far as Bourbon knows he's still covert except for (to him) the mystery man on the train. The FBI had nothing to do with that, so their reactions should be no different even after he thought he saw Akai. To be fair, though, he doesn't know for sure that the man on the train isn't connected with the FBI, and it definitely made him suspicious about Akai again, so he could be double-checking.
As for what Bourbon could possibly be investigating (if I'm wrong and it is him), I'd say that he's trying to see if anyone mentions his codename. As far as he knows, none of the FBI know his codename. So if they mention him, then he knows something is up. Not sure how he would get this information by disguising as a random person though, but then again Jodie did slip up earlier >_>. Disguising as Scar Akai would probably be better for this, since if the FBI avoids Scar Akai now instead of reacting to him as they did, then he might think he was discovered on the train. I don't think he actually is doing this though, since as I said earlier he didn't walk around near anyone important.
I'm not really sure what Akai's motive for disguising could be, since it doesn't seem like you could really get much information by disguising as a random guy

.
EDIT: Ah, almost forgot. Haibara not reacting to him doesn't really give us much information. She only occasionally reacts to Akai/Okiya, and even though she does react to Bourbon it's never really been emphasized, so it's unclear how strong the reaction is. Also, the man says that he was to the back side of Jodie during the robbery. I checked and didn't see him, but it's not like there's a great view of the background characters either.
Also, I should point out that while Akai wouldn't know for sure whether or not the person who taped up Jodie was a man or a woman (i.e. whether or not to say that it was his wife), he could easily say that his wife was taping up other people, and must have assumed that she taped up Jodie as well.
And, (hopefully) lastly, a possible (but, admittedly, flimsy) motive for Akai to disguise as a random guy would be to see Jodie's reaction to Scar Akai. Since he doesn't know exactly what the Scar Akai disguise looks like, he'd be unable to get it perfect (meaning the scar, obviously he could get the rest down perfectly

), so the only way he could see her knee-jerk reaction would be by disguising as this random guy. Plus, if she did know about Bourbon being Scar Akai, it would be risky if she reacted violently/tried to tail him (meaning Akai pretending to be Bourbon.... pretending to be Akai). Of course, he could also ask Conan, but we all know how little information is shared in this series >_>. Or perhaps he wanted to see her reaction himself instead of just being told? They did used to date so some emotional connection wouldn't be too unlikely.
Holy hell sorry for all of that, but there's just so much to talk about from this file! :D Can't wait to see what comes up in the rest of the case :)