Switch AppleCare+ from returned product

In the U.S., Apple provides a 14-day return policy if purchased from Apple, otherwise, it is between you and the seller of the Mac regarding their return policy. In Switzerland, the return policy may be different or not.

I do not believe that you can transfer AppleCare+ between devices. You can ask AppleCare to cancel it on the returned product and they will issue you a pro-rated refund on the unused amount to the original credit card used in the purchase, or by check. You can apply that refund against the cost of a new AppleCare+ purchase on the new replacement Mac. A canceled AppleCare+ policy on a device cannot be undone by the original purchaser.

You can verify the above with whom you originally purchased the MacBook Pro or AppleCare. I suggest you talk to the manager of the nearest Apple Store. No Apple employees participate in these fellow user supported communities so the last word on the above would be by contacting Apple.

Surely you know the keyboard generate raw keycodes, not specific letters, and that 'what letter is generated' can be changed using different language translation setting in your Mac, right?

And your CH keyboard already has Roman/English letters on the keys as well?

Do you really need to trade? if beyond the Apple 14-day easy returns, you may take a financial hit.