An helíyel swa-n híleng úni ("this sky is purple not") is also allowed; adverbs can go before or after the predicate adjective.
Answering "no" to that question might imply that one is still beating one's wife. To signal that that implication is wrong, úni is preceded by twak (indicating that something the sentence might imply is wrong); details are given at the end, after the conjunction útwek "but".
Úni mumwe is the noun phrase here; if úni was modifying the verb, it would be kíku úni nga mumwe.
*Úni iki úni mumwe would be double negation, so nga is required here.
TODO figure out what conjunction should go where "but" is. Also "with a heavy cudgel."