Yes you always have the possibility to manually edit automatic translations and you should do this.
Automatic translations are saved in your WP database so you only pay once, but as you know they are not always 100% accurate.
When you do not want to translate content yourself, we also have a built in translator user role. You can invite native local translators and assign them to posts, that they should double check. After they checked the post, it will be put into the status “pending review”.
This way you can let native people double check bot translations.