No one in Wano knew anything for the story to move further. Only Koshiro and probably someone from the Revos/Zoro's mom being a criminal/revo will know.
Which is factually false. Zoro looks like Ushimaru which was noted by Kawamatsu and Hyogoro ( and also Onimaru but Oda skipped it). I guess we can infer that Yasu and Oden’s father also see the ressemblance between the 2 men.
It was not hard that in the same chapter that Oden’s father talk about Zoro potential to turn enma black he questioned him about his lineage and then put 2 and 2 together : Furiko leave the country=> Furiko end up in EB and is Zoro grand mother => Furiko is Ushimaru’s sister => Zoro is from the Shimotsuki bloodline.
Yasu could have done the same thing and to stay in the idea of Zoro not knowing or not caring about isnloneage, this could have been an inner dialogue from the old heads but the readers would have known in the manga.
No one ever talking to Zoro about Ushimaru make no sense. The worst is really Yamato. She remember vividly “so-and-so” and she is supposedly a Oden fangirl but somehow seeing a so-and-so lookalike with enma (oden’s beloved sword) does not raise any questions from her.
This could have been easily adress in the manga.
