It is easier and
cleaner for a language like Lojban to split the two meanings into two
separate brivla, one that uses {nu} and one that uses {ka}.
Yes, I have seen {kaidji} and made {kaitcu} as well, but I'm not sure this is a sustainable route; we'd then need new brivla for every brivla where a {ka} belonging to x1 is useful as a substitution of {nu}, such as {gleki}, {nelci}, etc...