Learn Farsi: مباحثه را کارشناس هدایت کرد.

It follows the mo-C1-â-C2-e-C3-e pattern. If we extract the root consonants, we get b-h-s. You likely recognize this root from the word bahs, meaning discussion. Putting it into this Form III pattern adds the idea of mutual engagement, turning a standard discussion into a back-and-forth debate.

Why does the sentence start with the direct object (mobâhese râ) instead of the subject (kârshenâs)?

While standard Farsi word order is Subject-Object-Verb, placing the object at the very beginning is a common way to emphasize it. This Object-Subject-Verb order shifts the topic so the sentence reads more like: As for the debate, the expert guided it.

What are the literal parts that make up the word kârshenâs (expert)?

It is a compound noun made of kâr (work or job) and shenâs, which is the present stem of shenâkhtan (to know or recognize). Literally, an expert is a work-knower.

Would it be just as natural to say râhnamâyi kard instead of hedâyat kard for guided in this sentence?

Hedâyat kardan is the much better choice here. While both translate to guiding, râhnamâyi kardan is typically used for giving personal advice, offering directions, or showing someone the way. Hedâyat kardan implies a more formal steering, directing, or managing of a process, which is exactly what a moderator does for a debate.