Volume 6.5 was published in Japan June 25, v2025. Seven Seas has not given a release date for the translation, but will probably be several months away.
Google Books has this info:
Touko Amekawa · 2025 · No preview
The first collection of short stories in the series! Bonus short stories from the 50 short stories published in the "7th time the villainess has played a part in her life as a bride in a former enemy country" series published up to the first half of 2023...