Royal Society Publishing has recently published a special issue of Philosophical Transactions entitled "Modern perspectives in Proof Theory", compiled and edited by J. P. Aguilera, F. Pakhomov, and A. Weiermann.
The articles can be accessed directly at https://royalsocietypublishing.org/toc/rsta/2023/381/2248.
Purchase the print issue at the reduced price of £40 per issue by contacting sales@royalsociety.org.