There are only three ways to make your WordPress site multi lingual.
Use multilingual a plug-in such as Bogo, Polylang, WPML, Multilingual Press, and Translator.
Create a subdomain for each language and run WordPress separately on each sub-domain site, for example, ja.yugakurita.com, en.yugakurita.com, etc.
Enable the multi-site feature of WordPress and create subdirectories (subfolders) for each language , for example, yugakurita.com/ja, yugakurita.com/en, etc.
The easiest way to do this is to use a multi-lingual plug-in. If you google using key words such as WordPress and multi-lingual, most listed pages show you how to make your WordPress site multi-lingual using a plug-in. This site was launched in 2014, since I was originally a Japanese-English translator, it has always been a multilingual site since its launch.
I used a free, multi-lingual plugin named “mqTranslate,” which was popular back then. The plugin worked perfectly for a while. But after a year or so, the developer stopped updating the plugin and so the plugin could not work in WordPress 4.0 or later.
I stopped updating my WordPress and had clung on to WordPress 3.9.x for years. I missed out the latest plug-ins and there had always been a security threat. In this March, I finally gave up using the mqTranslate plug-in and upgraded the site to WordPress 5.1.
Originally each article on the website had two pages: one for English and the other for Japanese. I merged them into single pages by putting both languages on the same pages, that is, English appeared on the upper half and Japanese appeared on the lower half.
This hardly was a good solution. My website simply became less useful particularly for Japanese readers who had to click a link at the top of each page or manually scroll down to read the articles. It wasn’t SEO friendly either. Google doesn’t recommend you to put multiple languages on the same page.
Based on this experience, I don’t recommend making your WordPress website multilingual using a plug-in. Especially, if you plan to run your multi-language site for a longer period of time, never use a multi-lingual plug-in.
For this reason I would recommend you to use Methods 2 (Sub-domains) or Method 3 (Sub-folders) to make your WordPress website multi-lingual.
I was initially attracted to Method 2 because I had set up a couple of sub-domain sites such as memo.yugakurita.com and diet.yugakurita.com, so I thought it would be easier.
On the other hand, building a multi-site using sub-folders (Method 3) seemed a bit of a hassle. The procedure is more complex and it involves editing the wp-config.php file and FTP upload/download.
However, in terms of SEO, the evaluation of the original site is not effectively transferred to the newly created sub-domain site. It can also cause trouble when I change my server hosting service.
The rule of thumb is that if your new sub-domain site is not really related to the original site in terms of content type, creating multiple sites using sub-domains is recommended.
From a long-term perspective, I have come to the conclusion that use of sub-folders is the best way to make a WordPress site multi-lingual.
I did a big construction of the website the day before yesterday. Now all Japanese posts are on “yugakurita.com/ja.”
It isn’t too complicated to make a new WordPress multi-site using sub-folders. This site however is 5 years old and I encountered some problems while changing the site into a sub-folder-based multisite. I will show you how to do this in the next article.