Excel search range and return corresponding column number

Question

I am trying to make my excel document search a range and return the table value of every incidence. In the picture below , I am trying to enter a formula in the leftmost (green) cell that will search the table (bold outline) for all instances of "Piercing", then return the position of each instance (The corresponding number in the blue row) as a list. What I have in the green cell is what I'd like it to look like. If necessary, I'm ok with it not showing duplicate entries and instead just showing where one of the instances is.

Answer 1

Try below formula-

=TEXTJOIN(",",TRUE,FILTER(C1:L1,MMULT(SEQUENCE(1,ROWS(C2:C4),,0),--((C2:L4="Piercing")))))

And if you have BYCOL() function then could try-

=TEXTJOIN(",",TRUE,FILTER(C1:L1,BYCOL(C2:L20000,LAMBDA(x,MAX(--(x="Piercing"))))))