Depends on your purpose of the transcript. If you are expecting the exact form of the words spoken in written form, then any deviation from that is no longer a transcription. At that point it is text loosely based on the spoken content.

Once you accept it okay for the LLM to just replace words in a transcript, you might as well just let it make up a story based on character names you've provided.

> any deviation from that is no longer a transcription

That's a wild exaggeration. Professional transcripts often have small (and not so small) mistakes, caused by typos, mishearing or lack of familiarity with the subject matter. Depending on the case, these are then manually proofread, but even after proofreading, some mistakes often remain, and occasionally even introduced.