That multisearch thing looks to me like an entirely different thing. No, I'm talking about essentially the same method to pick out substrings as you, albeit a bit more generalized. It seems useful, but it shouldn't abuse the range operator syntax. I think one should be very restrictive with extending operators to do things they weren't meant to do. If the analogy isn't completely apt, then don't do it; you can just as well make it an ordinary function instead.
In this case it breaks since the ordinary range operator lets you express "give me the range that starts at the third position", but the analogous case here, namely "give me the substring that starts at the third occurrence of this string", can't be expressed. Also, what you have described is that the range operator is extended to solve a special case that you found to be convenient right now (the left substring is the first match, and the right substring is - for no good reason - the first match after that one). That's not good enough to make it standard behavior.
