I don’t think Boba is important enough to explicitly mention in the crawl, but the idea that he is there anticipating that Luke will come to the rescue is interesting. Maybe give Boba new dialogue during the sail barge battle. He could tell Luke something like, “You’re lucky Vader wants you” or “You’re worth a fortune to Vader.”
Or during this new Boba scene he could say something about Vader wanting him. Something in the vein of, “I was expecting the Jedi. He’s worth a fortune to Vader.”
Either way, it is a good explanation for why he’s hanging around. Maybe he couldn’t convince Jabba to give Luke to him after he killed his Rancor, or maybe he knew Luke had something up his sleeve, but he took the first opportunity when hell broke loose to try and capture him.
Maybe when Boba first lands on the skiff, he could either say, something like, “Don’t move Jedi” or “Surrender”. Boba could try to get a shot off before Luke slices his blaster, or we could see that Boba tried to stun him but he either missed or Luke deflects it, but with how quick it is it might be hard to do that. The important thing is that we see Boba is trying to immobilize Luke rather than kill him.
Which works out well with what Boba tries to do next, which is tie him up. I was thinking it would be cool to add a yellow energy effect to the rope with some electric sounds to make it seem something that would be tough enough to restrain a Jedi, but that might be overkill.
And this idea works well with the idea of Boba shooting his hand, because that would clearly show that Boba is trying to immobilize Luke and take away his ability to fight back, rather than just shoot him in the back of the head and call it a day.
Either way, it does add a little more nuance to his presence in ROTJ and the entire first act. And while this idea is already there, this would make it clear that Boba’s greed was his downfall.