KTM to Hongkong to USA
Did any Nepali passport holder recently(dec 2019) travel to usa From KTM using Cathay pacific via Hong Kong transit?
Was transit visa required?

Transit Visa is mandatory if you're switching to AA. You will be denied boarding either in KTM or sent back from HKG.
https://www.evisahongkong.com/transit-visa/

https://www.immd.gov.hk/eng/faq/visit-transit.html

Yup. I did recently (November). To and from LA-KTM-LA. With family. All Nepali passport holders. No problem at all. Cathay Pacific has an agreement with Chinese govt that passengers (Nepalese) flying via CP should not require HK visa, as long as they do not change their flight CP to any other.

This information might be kind of old, and pardon me if I am not up to date with recent changes. I got assured with this information before traveling. And, in fact i did not have any trouble.
https://zentravels.com/do-nepalese-passport-holders-need-a-transit-visa-to-travel-via-hong-kong

you are correct SD

Anyotherairlines+CathayDragon NO GO
Only CathayDragon GO GO

What about Dubai? Do we need transit visa for 16 hrs layover?

dubai ma chaiinna, not needed.