have had many scenarios like this both good and bad with luggage

If you are flying multiple airlines I always bring a small carry on board to last you a few days just in case the checked luggage is delayed. Most likely your luggage will be fine but Id play it safe.

Hong Kong is a great airport i think your luggage will make it no problem but i woeuodl ask an agent in the morning to see if the luggage checked in. In Nairobi i think i would be much more skeptical. Good luck both of you