Does work (regardless of C4 contents):
=INDEX(Details!$J$2:$J$50000,MATCH('Vulnerator Translator'!C4,Details!$P$2:$P$5000,0))
Does not work (if C4 is a formula):
=INDEX(Retina!$C$3:$C$10,MATCH('Vulnerator Translator'!C4,Retina!$A$3:$A$10,0))
However this second one will work if the content...