Your fr_reverse_charIndex function can be rewritten as:

alter function [dbo].[fn_reverse_charIndex]

/*********************************************************/

/* CREATE fn_reverse_charIndex */

/* ---------------- COMMENTS ------------------------ */

/* Give the last occurrence of the character passed in */

/* ---------------- HISTORY LOG ------------------------ */

/*********************************************************/

( @char char(1), @expression varchar(255))

returns int

as

begin

ifcharindex(@char,reverse(@expression)) = 0 return 0

return len(@expression) - charindex(@char,reverse(@expression)) + 1

end