Alternate Writer upobir(Sabbir Rahman) came up with a nice solution.
If we choose A and B such that $A + B - 1 = L$
then the functions can be defined as:
$F(A,B)$
= $(R-A+1)\times (C-B+1)$
$G(A,B)$
= ${L-1}\choose{A-1}$
We can also write $F(A,B) = F(A,L-A+1)$
and $G(A,B) = G(A,L-A+1)$
It can be proved that log of the above functions are ternary searchable, so log of $F(A,B)\times G(A,B)$
is ternary searchable also.
Time complexity: $\mathcal{O}(T\times \log_\frac{2}{3}{L})$
Space complexity: $\mathcal{O}(L)$