It is not that tricky to translate the website, but it is quite hard to make SEO work for your localized pages and get a stream of users to these pages.
I don’t use separate domain names for translated pages. And for some languages it works well (like for Spanish).
But doesn’t work for some other languages. I guess search engines analyze and count external organic inbound links to the localized page and ignore internal links / SEO links to localized pages. Or maybe they count only links that bring real users and measure the bounce rate of these users.
Some of my localized pages are 2-3 years old and still don’t get organic search visitors. For example Japanese.
It would be nice to know exactly how to “activate” localized pages to make Google love these pages.
Right now I am experimenting with Chinese language because their economy seems more protected in this coronavirus year. But that is hard. They have their own analogs for twitter, youtube and Facebook. And it seems it is very hard to even register an account in their wechat and other services if you are outside of China