Hi @Basildonnewts, let me see if I can help out here.
To my knowledge there is no setting available in what's app able to translate messages. However, since What's App is not created by us here at Sony, You might be better off asking the What's App support. You can find their helpcenter in the link below.
https://www.whatsapp.com/contact/
I hope that helped a little bit!
