Per Merriam Webster, an interrogation is "a formal and systematic questioning," which is exactly what is called for when examining a proof.

Personally, I use the word "interrogate" when I want to question an idea without implying I want to discredit it.

https://www.merriam-webster.com/dictionary/interrogation

It's a common (most common?) word in mathematics in this meaning.

You interrogate a proof.