"Wageni wanakuja Jumapili."

Translation: The guests are coming Sunday.

[liuhsu]

Shouldn't the translation be "the guests are coming ON Sunday"?

[juryrigging]

Technically, yes, but I would say that "the guests are coming Sunday" is also informally correct.

[Catriona28475]

I think "ON Sunday" is more typical in UK English and just "Sunday" in US English. Correct me if I am wrong! (I'm British and I say "ON Sunday".)
So I think both answers should definitely be accepted.

[ElMeuNom]

I'm American, and I have heard and would say either.

[Norman501963]

"ON" is missing.

[dibsmft]

'The guests arrive on Sunday' is apparently wrong. Eish!

[JasonFries2]

Coming and arriving are 2 different verbs with 2 different meanings