You might try
[B4] = OFFSET('Main Data'!$A$1,ROW()-1,MATCH($B$1,'Main Data'!$1:$1,0)+COLUMN(A1)-2)
Then drag down and across.
EDIT
or non-volatile version (range may grow)
=INDEX('Main Data'!$A$1:INDEX('Main Data'!$1:$1048576,COUNTA('Main Data'!$A:$A),16000),ROW(),MATCH($B$1,'Main Data'!$1:$1,0)+COLUMN()-2)
or fixed range version
=INDEX('Main Data'!$A$1:$EE$15,ROW(),MATCH($B$1,'Main Data'!$1:$1,0)+COLUMN()-2)