Use the SWITCH function:
=SWITCH(IFERROR(INDEX(FILTER([Recording.xlsx]Wednesday!$D$2:$D$26,[Recording.xlsx]Wednesday!$B$2:$B$26<>""),ROW()-2),""),"Y","Accepted","N","Refused","")
This way, you avoid using an auxiliary cell, and most importantly, avoid repeating the whole call to IFERROR(INDEX(FILTER())).
Indented view for better understanding:
=SWITCH
 (
    IFERROR
    (
        INDEX
        (
            FILTER([Recording.xlsx]Wednesday!$D$2:$D$26,[Recording.xlsx]Wednesday!$B$2:$B$26<>""),
            ROW()-2
        ),
        ""
    ),
    "Y","Accepted",
    "N","Refused",
    ""
 )