If you are looking to set a different featured image for a translated product without using the Media Translation plugin, I'm afraid that won't be possible. The primary function of the Media Translation plugin is to enable the setting of distinct images for each language.
That said, you do have the option to manually edit the translated product and upload its featured image. However, this method isn't ideal. After updating the translation, the manual changes will be replaced. I hope you can understand.
Please let me know if there is anything else if you need help. I will be happy to assist.
