I still don't understand what it was Fredo thought he was going to do to get Mike to go easy on the "negotiations." It is even more perplexing that Fredo seemed legitimately clueless about the family making an investment with Roth in Havana. What other "negotiations" were going on? It wasnt over the Tropicala because Ola already told Mike that Roth gave the ok to the deal.
It could have been over the Tropicala. We don't know how long ago Fredo "bumped into" Ola. But, really, I doubt they told Fredo, and I doubt he even thought to ask. He was blinded by the opportunity to make something on his own.
The late-night phone call shows that Fredo realizes he was lied to, making it likely that he didn't know it was a hit. But the question remains: What information did Fredo provide Roth, and how could he have possibly thought it would have helped in a negotiation?
"A man in my position cannot afford to be made to look ridiculous!"
