Is it permissible to use the word "Al-Kareem" (the Generous) to describe people, such as "the generous master" (Al-Sayyid Al-Kareem) or "my generous brother" (Akhi Al-Kareem), and will a person be held accountable for that, taking into consideration that "Al-Kareem" is one of Allah's Most Beautiful Names?

There is no blame for expressions that linguistically share names and attributes. Allah described His Throne as "Al-Kareem" (the Generous/Noble) and described Himself as "Al-Kareem." The Prophet, peace and blessings be upon him, described Yusuf (Joseph), peace be upon him, as "the noble son of the noble, son of the noble, son of the noble."