I have never seen software that does BOTH translation and conversion. I have the feeling it would be horrifically hard to do, because the computing behind translation and determining context would be so difficult.

If anyone does it, it would be Nuance link because they are up front in the voice transcription world.

There are some. You can web search “simultaneous translation app” and readily find things.

I’m not really clear what your specific requirements are.

Do you really want it from an .mp3 file, and into text in both the language it was spoken AND the other language in text at the same time? If so, I think that might take a little looking around, and/or to use some combination such as another app to play the mp3 file. But I expect some program will do it if you look long enough, as there are many translation apps.

Typically they are more like they listen on a microphone and translate into text in one language. Often multiple languages are supportable by one program.

How good a job they do, I don’t know.

Here’s an article describing five mainstream phone apps for translating.

Here’s another article describing 15 such programs