Multilingualism on one site or two domains, how to support such projects?

Question

Google

Hello. I will divide the question into two parts:
Question from the point of support of the project on two domains:
Tell me how to properly support the same (the difference is only in domains and language) projects. Previously, the project was on the same domain for the ru audience, in fact, it was synchronized with the locally developed one. Now the site has been moved to .com and we need to make some changes to two projects at once, whether there are any features and so on, enlighten us on how to support such projects correctly and without problems. I store all the data in two different databases.
The database will differ only by max two tables (one field each) Can it be easier to make a table with two fields for ru content and English? How to implement everything "on a whim", I'm afraid that it can then turn into a nightmare, until it's too late to fix everything. Help to unravel, before I had to enter two markets.
Question from the point of optimization in search engines:
Faced such a task-problem. Initially, I created a project on the .ru domain, there is little traffic, but there is twice as much traffic abroad. Therefore, I transferred the site to .com and translated it into English, the traffic went to .com much less often.
Now there is a big problem with the support of almost two projects. The content of the ru and eng versions on the site only differs in the description for the cards with a maximum of 250 characters, that is, there is no need to translate hefty articles there. Does it make sense to make multilanguage on .com? Also, users have the opportunity to create these cards themselves with the same description, which will actually cause confusion, people with ru created a card in ru, from English to English, it’s not good, as I understand it, you shouldn’t mix it like that?...

Answer 1

We take Wordpress and turn on the multisite mode.
The main domain is the main blog, in the main language, let's say Russian.
Each new language is a new site on its own subdomain.
How to link to the site not a subdomain, but a new domain? Reading the WordPress Code Multisite Domain Mapping
How to sync content between blogs within WP? There is a plugin Multisite Post Duplicator
Advantages of this solution - user #1 on the Chinese domain created a card about something, so it will be visible only on the Chinese site. It doesn't work for other sites. In this case, there will be no mixing of data, unless you specifically write some kind of plugin for this matter.
I will say even more, you can localize the admin panel and the site itself for each language. It is very convenient from the developer's point of view if native speakers who do not know the main language of the site are engaged in the content.