There is an issue with wildcards in structural replacement, specifically when attempting to replace characters within a pair of brackets containing a comma. The wildcard placeholder (<wildcard|x>) returns only the placeholder itself, not the character it is supposed to represent.

For instance, in the attached document, using C-R to initiate the "Search and replace" window and typing (<wildcard|x>,Y) should yield replacement results like (<wildcard|x>,Z). However, the actual results display only as (<wildcard|x>,Z) instead of the expected (X,Z), and so forth.