I have read the documentation:
"MAT_BOOKING_ALL_DETAILS_HTML helps you saving much time, instead of writing every fieldname you can use this one to display all booking details, including all fields. MAT_EVENT_ALL_DETAILS_HTML does the same for the event data. If you use the non-html version you use _TEXT instead of _HTML."

But using this the "old" additional booking fields are not listed in the confirmation emails. Please help me!

Best regards
Jürgen