how to write text formula which involves multiple txt variables

I'm working on massive 301 redirect project. My site was translated into over 50 languages, each page of each language cached in the search engines.

Now that i have revised the site I'm getting lots of 404's which is not good for SEO.

So here's the challenge:

The "bad" URL will look something like this:

HTML Code: 

I want to redirect to

HTML Code: 

Other variations of "bad" urls might look like this:

HTML Code: 

HTML Code: 

HTML Code: 

What I need to do is search for the language and create a new, concatenated cell which will begin each new url with the appropriate language.

Can someone assist me with a formula? I've attached a workbook with examples.

Thanks.

Create the name seq referring to the formula =ROW(INDIRECT("A1:A256")). If a url to be changed is in cell A5, try the following formula.

=IF(COUNTIF(A5,"*/??/*"),MID(A5,SEARCH("/??/",A5),4),"/")&CHOOSE(MATCH(2,1/COUNTIF(A5,"*"&REPT("/*",{0,1,2}))),
"",SUBSTITUTE(MID(A5,FIND("/",A5)+1,256),"old-","new-"),MID(A5,LOOKUP(2,1/(MID(A5,seq,1)="/"),seq)+1,256))&"/"

This isn't a task for which Excel is well suited. Any scripting language would be better suited to this type of text transformation.