And to me a Sneak attack means a character is actively fighting sneakily to get an advantage since Sanji wasn’t doing that it just means underestimated Sanjis speed and just figured he’d be able to kill Bonney by the time Sanji showed up cause as we all know, Nesjuro didn’t care if he got hit. If Franky heard him Nesjuro was literally right there and should’ve been able to hear the same especially with his CoO he showed off.
IMO if Oda wanted to portray this as a sneak attack, it would’ve looked closer to the oven scene in WCI where Sanji actively wanted to avoid being seen but it felt more like Sanji wanted to make himself a target here to distract Nesjuro from Bonney.
You are under the assumption that everyone on the battlefield can hear yelling which isn't true.
Have you been in a situation of loud crowd?
Two friends standing next to each other might end up hearing totally different things because it's all about focus.
Venus being next to Franky doesn't mean Venus heard it.
Second, for CoO to come into play Venus needs to focus on it. If he's distracted on something else then even with CoO in loud battlefield he might not hear it.
Third, Oda didn't portray Venus as if he heard it. Until the end, he was focus on his sword swing.
So, in manga, where Venus had no reactions to Sanji's yelling is cannon - he heard it is headcannon.
And, you know it's best for you all to go with this argument coz let's assume he heard it then this is even worse because it implies Venus didn't even give a fuck about Sanji.
All that blood means nothing when they can heal.