You're entitled to call things as you wish, of course, but your definition of "vibe-coding" differs quite a bit from mine.

500k lines in 11 days? With 8-hour working days that's 100 lines per minute. There's no way you're comprehensively reviewing code that quickly.

The code was generated by a LLM, and the output wasn't even read by its user. That's definitely vibe coding.

It's a direct translation without changing the overall code structure or data structures. I do think this process deserves a distinct name from blind whole-of-project vibe coding.

Translation does seem to be a strength of LLMs, and as they said in the post, the code at the function-level all still feels familiar to the team. They've also already moved users to the codebase without anyone noticing; that's a better result than typical vibe coding.