Run Rosetta on macOS Sierra
You can try installing Snow Leopard (OS X 10.6.8) in VirtualBox. I was able to do this using an iMac (21.5 inch, Mid 2011) with High Sierra installed. I was able to install and use Adobe Create Suite 2 in a Snow Leopard (OS X 10.6.8) virtual machine.  Adobe Create Suite 2 requires the installation and use of Rosetta.

VirtualBox is a free application.
I can not longer find the link to buy Snow Leopard from Apple. Used DVDs are available or you can refer to this answer.

Below is a link for the license for Snow Leopard. As far as I can tell, Apple requires the use of a Mac to run Snow Leopard. There is no mention of whether or not the Mac uses a virtual machine. 

https://www.apple.com/legal/sla/docs/osx_snow_leopard_sec_upd.pdf