does an act of worship that is fardh kifayah like funeral prayer, means that the knowledge about that act of worship is also fardh kifayah to learn?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Learning the Sharee‘ah rulings pertaining to a communal obligation (Fardh Kifaayah) is also a communal obligation. Accordingly, learning the Sharee‘ah rulings pertinent to the funeral prayer is a communal obligation. At-Tahaawi said in his book Haashiyat At-Tahaawi ‘ala Maraaqi Al-Falaah Sharh Noor Al-Eedhaah: “…and you should know that learning any knowledge that enables one to perform an individual obligation is an individual obligation as well, such as the learning related to knowledge of Allah, The Almighty, the prayer, Zakah, fasting, Hajj, what is lawful and what is unlawful, etc. Similarly, learning any knowledge that enables one to perform communal obligations is itself a communal obligation.” [End of quote]

Allah Knows best.