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",
""
)