Find the (n) matched of string in a string.

simple....not quite
generally a combination of formula's like you have done would be required

based on your example....you want to find the string after the 2nd occurrence?

here is how i would of done it

assuming a2 is the cell you want to extract

Formula:

=LEFT(A2,FIND(CHAR(95),SUBSTITUTE(A2,"+",CHAR(95),2))-1)

char(95) [which is _ ] can be replace with anything you want...but should be something that does not appear in string itself
What this formula does is find the 2nd occurrence of "+" and replaces it with "_"
then it finds where _ is and left formula kicks in to return text up to where "_" was found