I was going through some recent history and transactions in a platform and then it crossed my mind that some complaints were being made about unreflected payment and transaction id were being sent to show proof and then these person's later got credited.
But I ask, is it possible to fake a transaction ID and still be undetected?
Which platform are you talking about like if that platform is based on blockchain technology then yes you can track the status of that transaction and once the transaction is made it can not be tampered with. Because in blockchain one can fake the TX but not the ID because each transaction have different ID and if the person sends you a ID then that transaction is publicly viewable and you can see the status and details like how much amount that TX have.
That's the beauty of BTC blockchain that, if one try to fake things out that TX can not be confirmed and validated by Validators instead that will be marked. Or if not marked then at least one could confirm by seeing the details by searching the transaction ID on Explorer.