T222092 was rejected in 2019, not sure about the current status of support though.

I have discussed these on the MediaWiki and MediaWiki-i18n mailing lists previously, some people advised me to start the task.

In T318343#8254819, @Stang wrote:

T222092 was rejected in 2019, not sure about the current status of support though.

@Stang thanks for the comment. But the previous task was rejected due to inactivity of the administrator. In the present cas, a discussion has held. And according to the comments the task should be resolved.

This request is at this time hard to implement as the tool is heavily tuned towards Wikipedia. @Pginer-WMF has a longer explanation in an earlier thread on the same topic:

For now, Content Translation is mainly focused on the translation of Wikipedia articles. The tool is able to process wikitext so it should be capable to work in different projects. However, dealing with complex pieces of content such as templates that are fragmented across languages still brings some challenges and we think it is best to improve in one project before opening the scope more. It makes sense to consider other projects but that is not in our immediate roadmap.

If there is a particular project where you expect support to be easy and particularly useful we want to hear to consider for future plans.

Meanwhile, you can use the tool ability to translate pages under the user namespace to translate contents from other projects. For example, copy contents from Wikivoyage into a Wikipedia page under your user page, translate that page with Content Translation and copy the results back. This is not ideal, but can be useful in some cases.

However, we do plan to review the state of things after completion of ongoing work as it would definitely be helpful to have Content Translation available for other projects as seen in these conversations.