Well I dont think ZR is considering Juma for the VNL so I think Macris would be Naiane's backup for the first week at least. Or maybe Roberta but I think her season has been more demaning as she's played more sets.
It's true that Ac need international experience as starter but you cannot also force it and make her play 2 weeks or so after her last game, no matter how young she is.
There will be 3 weeks since her last game (she won't play CL final). It is always challenging ofcourse for players playing finals but that's the life they sign up for, which comes with other perks🤷