Great Idea ! Mind if i borrow for my own project ? Such a simple solution, because if indeed a valid transaction was created, a re-broadcast would resolve it.
It's not a new idea. There have been services offering to broadcast transactions for people since shortly after Bitcoin was launched.
See
https://live.blockcypher.com/btc/pushtx/ for a good BTC one for instance. It lets you decode a transaction without broadcasting if you want to check that the fee is reasonable for example.
Oh, i know that. But i mean having it as an option WITHIN the exchange. So if a problem arises, a user can check the transaction and/or re-broadcast on demand.