As it is today, the authoring tool doesn't have multi-language support (either in the interface, or the output content). As Simon's said, some labels are dynamic, but more work needs to be done.
This is a feature we're eager to get in asap, and at least one of core collaborating companies has a big need for this, so we've already pencilled in a milestone to tackle this (as soon as we can secure some developer resource!). However, due to the existing priorities and commitments the core team has made, this isn't likely to be attempted until late in the year (maybe longer).
If you have the resource to available to take this on, the Adapt team would be more than willing to help out in any way you need it, be it planning, development, or testing.
Gitter may be the best to discuss this in the first instance, with a view to perhaps setting up a call in the near future if our needs align?