Has a Two Key TDES encryption ever been successfully attacked? Is there any known instance of a Two Key TDES ever being successfully attacked (in real life), when the key is used to encrypt less than $2^{20}$ words?
If we talk about key search attacks (rather than key compromise or/and side-channel attacks), the answer must be no, for the best known method is impractical.

On the other hand there has been numerous successful key-recovery attacks against devices using TDES, including on some that try hard to avoid it. One example here, another there.