Glad to be of service! DeepL is an amazing tool most of the time; I'm glad you found the link useful. This book review on practices in Swabia may yield some more practical information (again, DeepL might be your friend), as well as this feature in Süddeutsche Zeitung may be helpful, too.

I found a legend from Passau (17th c.) that mentions the swallowing of protective letters ("Zeddel" in dialect; Zettel in today's German is a paper note or small sheet of paper), here.