I actually don't know how to do that. All I can suggest, at present, to fork https://github.com/rinigus/osmscout-server , make a new subfolder under docs, like

docs/fr

and insert translated index.md together with html files and screenshots under that directory (docs/fr). Styles and used JS can be all linked from there.

I guess we need the first brave translator to do that and all others would follow. Not as simple as for the main app, but should be doable.

Or is there a better way?