Not sure if these are indeed "new"/untranslated Dhamma talks by Ajahn Chah, but also in the Abhayagiri book list is the following volume (downloadable as .pdf):
https://www.abhayagiri.org/books/517-st ... wing-water
Still Flowing Water
Ajahn Chah
Year Published: 2013
A collection of eight new or significantly revised translations of Ajahn Chah’s Dhamma talks by Thanissaro Bhikkhu.
Two of them have never been translated before into English, and four of them are based on entirely new Thai transcriptions of the best and most complete source recordings available.
Maybe it might be helpful for you, Santimuni, to skim through the complete book list, as there are several more volumes about Ajahn Chah, which all also can be downloaded right there:
https://www.abhayagiri.org/books
The teaching is a lake with shores of ethics, unclouded, praised by the fine to the good.
There the knowledgeable go to bathe, and cross to the far shore without getting wet.
[SN 7.21]