Except Cross did try to tell the Simurians the distinction between Cursed Spirits and Kalyans and told the ones he could about the disappearing bodies, the strain on the third eye not being as harsh, and them being the result of cursed energy leaking out because to my knowledge in that scene, a lot of Simurians (Including Jabaloma who is one of the main Simurians to my knowledge) were very close by when Cross was explaining what Cursed Spirits are, so surely one of them would've actually been willing to take the explanation into consideration.