It took a lot of balls for him to trust Lando and continue the assault on Death Star, but he did exactly that. Inventor of the B-Wing. RIP.
He didn't invent the B-wing...that was just one of his kind. And I'm nerdy enough to have seen that episode of Rebels.
Did they retcon it? Can't remember the source material, but it has been stated a long time ago that Ackbar lead the group that designed it.
Wicki references page 3 of Sansweet's book, and he works for Lucas Films. But I'll let you Star Wars geeks work this one out.