The SO Pinyin Slugs plugin is a fork of the original Pinyin Permalinks plugin, because the developer never responded to any communication.
We adapted the plugin in such a way that the slugs of the non-Chinese language remain untouched and only the Chinese character slugs will be transformed into pinyin (a problem of the original). And since September 2020 Pinyin Slugs also transforms Traditional Chinese into Pinyin, next to of course slugs in Mandarin.
Chinese characters don’t come out good in permalinks. Without the SO Pinyin Slugs plugin activated, the example post I made for the screenshot will get a slug like this: %e6%90%9c%e7%b4%a2%e5%bc%95%e6%93%8e%e4%bc%98%e5%8c%96. With the plugin the slug automatically becomes sousuoyinqingyouhua.
Search engines such as Baidu obviously cannot make much of the first slug, but they can handle pinyin perfectly, especially when it is written as one long string without hyphens or underscores.
So instead of transforming “中国” into two separate words divided by a hyphen or an underscore (the original plugin has this as options), it is best transformed into “zhongguo”. The only option Pinyin Slugs therefore has left is the length that you can limit to an x amount of letters. The default is 100, which should be plenty for most.
WPML has published an article on How to Build a WordPress Website in China and Reach an International Audience where the Pinyin Slugs plugin is featured.Credits plugin header image: Joschko Hammermann