With Helper.gg you're able to change the default translation language, by default it is "English", although if you want the bot to translate every message into a certain language you can.
Step 1: Logging into the panel
To do this you need to log into the panel at:
Step 2: Clicking "Modify"
You need to select your server, then select "Modify"
Step 3: Clicking "Commands"
You need to click "Commands", then click "Translate Command" then select "Message Values"
Step 4: Setting the default language
On the "Translate Guild Language" option, change that to the default language you want the bot to translate ALL messages too.