Google Translate
We provide our website in 8 different languages. We translate from english into X with Google Translate. We use ngx-translate (angular) to allow switching between languages on the fly.
I then took this whole system, changed it from being json based for the translations and converted it into TS class based. Translations are stored in the DB and upon login, read in for the account and assigned to the params in the class. These are the base translations that come from Google.
A few custom components later and an admin of the account can toggle "editing" of translations so IF a Google Translate comes out wrong, they can change it. This also allows the user to customize the UI, for example: If they want "Dashboard" to be called "Reports" - now the user can do it at the account level and it trickles down to all their users.
They can also change the base English translation for any given string for their account to something different, and if they don't know the translations for the other languages, a simple click of a button runs that new string through Google and translates it into the rest of the languages we support for them. If the outcome is good enough they're done. If not, they can edit those on the fly as well.
A NodeJS script takes all the params from the base english class file, runs them through google translate for all the languages we support and updates the DB when we add new translations. This is only for new strings we add. Any existing translations the user "override" remain intact.