(I'm the author of the Cantr Webzine post you quoted)
I've been using Cantr to practice Spanish and later Portuguese. You're supposed to have at least some working knowledge of the language, so that's one thing, and there are plans to better define this and encourage language learning.
Survey of Players
Seeing this as a good opportunity to get insight from players on their use of Cantr to learn languages, I just surveyed players and got back 167 responses. About 24% said thay play Cantr in a language other than their own.
Future languages
There was quite a variety of responses in terms of languages people would be interested in playing that they don't currently. I don't see Chinese, but if even one other person can be found (to have someone else to speak with) that may be enough to open the language again, as well as others.
Concerns
There are two main concerns among players that discourage them from playing a character in another language.
- Don't know the language well enough to communicate or understand well.
- Lack of time to dedicate to play in another language.
Other concerns:
- Lack of translations for things in the game. Just this week I had an idea to help with that- we may be able to use automatic translation until volunteers (players) review and correct the translations (note that Cantr is completely run by volunteers).
- Enough other players to practice the language with.
Positive things expressed by players
- Seeing examples of language use by natives, and practicing with natives.
- Learning by exposure to the language where your character meets other characters of that language. Someone expressed that this experience encouraged them to learn a new language.
- The multi-lingual dictionaries created in game for characters (and their players) to use.
- Being able to practice Esperanto and Lojban, whereas it's relatively hard to find such opportunities elsewhere.
- Interacting with people of other cultures.
Conclusion
The effectiveness of Cantr to learn languages, as with language learning in general, depends much on the effort an individual puts into it, as well as the activity of other players. But Cantr does provide a slow-paced way to practice language and to have something interesting to talk about due to the society simulation aspect. Content and society is created completely by the players, so it's not just translations you're looking at, in terms of notes written by characters, etc. in addition to the translated mechanics of the game and many technical terms.