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That shouldn't be a problem for Carrot, or Yamato or anyone, really. It's extremely unlikely the SH won't get out of Wano without a proper bounty raise, so however it happens, the events taking place in Onigashima will be known and taken into account.
The same way the Marine magically knows what took place in every arc and who defeated who and who deserves a higher bounty within the crew (Chopper aside for gag reasons), they will know it again and any new entry will be included.
Those arcs where they get bounty raises, there always been Marine/WG presence, namely Alabasta, Enies Lobby, Dressrosa. and Morganz leaked the events of Totto Land and was responsible for Luffy's latest bounty.
here, there's only Drake, and I suppose he'd put special attention in who's taking down the biggest names around.
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I find it almost impossible that he wouldn't notice someone who was part of the fight against Big Mom.
The BM Pirates knew about her, but since news of those events already have been spread around, and no one else but Luffy had a raise from that, I'm assuming Carrot could only get a bounty from what she does here, depending in how big of an action it is, and if Drake witnesses it, otherwise she'll go unnoticed once again.