
We've had requests since the earliest days of Mudlet for Chinese, Russian, Polish, Spanish, and other languages. Mudlet 4.0 will be all about making Mudlet work with them.
There are many aspects to internalization (i18n for short) so I'd like to lay out a reasonable roadmap for this work. As there are a lot of aspects to this, I think we should do this in a step-by-step manner and make minor (3.x) releases as we add support for the next step. Tackling everything at once with our limited resources would be impossible and take another 4 years to get a final version out.
I think a reasonable roadmap is the following:
1) support for displaying other languages in the main window
2) support for working with text in other languages in Lua
3) translating the Mudlet user interface itself
4) translating the documentation
5) translating the API functionality
The roadmap is available as tickets on Github.
#1 is the most vital because without it, Mudlet is just impossible to use. Once #1 is in, you can at least use the client - this in fact what the Spanish (source) fork of Mudlet does. Speaking of forks, there are at least Russian and Chinese versions of Mudlet as well.
I invite all (future) users of Mudlet to post in this thread with their experiences with translated software, wishlists for Mudlet, and feedback on the proposed roadmap. If you've already been working on adding i18n support to Mudlet, please join us on Github to join our efforts

PS. Broken English accepted here, feel free to use Google Translate if need be.