excel complex formula

gistfile1.txt

If you want to find last value of the column

K1 is start of upper header, U6 is end of current row
we want to find header of last non empty column in a row (for K to U columns)

=ifna(index(filter($K$1:U6,not(ISBLANK(K6:U6))),1,counta(K6:U6)),"TBD")

This selects subset of non empty cells from K1 to U6 (from first row to current row)
FILTER AREA
=filter($K$1:U6,not(ISBLANK(K6:U6)))

from these non empty cells 
index(reference area,row, column)

from filter area we select first row, and last non empty element (counta(K6:U6) gives length or count of non blank elements)
=index(FILTER AREA, 1, counta(K6:U6))

then remove #NA with TBD
=ifna(value, "TBD")