Hello,
For an online use, the goal of the application is to be more comfortable than the web site, especially when you use it on a tablet with a touch screen. And for an offline use, it's very nice to save your caches into offline lists and download them on your GPS device and if you have a tablet with a GPS you can use it to go until the cache.
The application is in French and English. Windows selects automatically what seems to be the best language for you. To change them, go to in your control panel in the section "Clock, Language, and Region", click "Language" and here keep only "German (Switzerland)" and remove all the other lines (especially if you have a French line) and open again the application. It will be in English.
I will try to translate in German in a next version.
Valentin