thegeneral
I have changed the web-site to use your revised wording. Thank you again for giving me such excellent and complete feedback.
When TARDISgo is fully ready, I hope you will give it a try, then write to me in Chinese to tell me how you get on!
Yes, GopherJS is not only more mature, it is also a really great project. If you want to target JS today, you should use it.
By contrast, TARDISgo not only targets JS, it also targets C++, C# and Java (plus some other minor languages). In addition it gives access to the rich Haxe cross-platform development ecosystem.
I am actively developing the project, but that work is not yet visible on GitHub because of breaking changes in the Haxe compiler. The project will get a major upgrade once it is stable with the new version of Haxe (3.2.0). This upgrade will raise the number of standard packages which pass their tests (for at least one target language) to 80.
Major announcements about TARDISgo will appear on twitter @TARDISgo. Please stay tuned!