"We will wake up the guests"
IMO tu-ta-amsha wageni is correct and - most important - you will be understood quite well (because the object wageni (=guests) is mentioned).
Advanced swahili skills are shown when saying tu-ta-wa-amsha wageni adding the 3rd person plural object infix wa (=them) while the object wageni is still mentioned (edit: IMO this places emphasis on the object = the guests, hence this can be considered the most accurate translation).
Of course, without mentioning the object wageni the object infix wa becomes mandatory, e.g.: Wageni wanalala hotelini. Nitawaamsha saa moja asubuhi.
Kuamka and kuamsha can both be translated to English as "to wake up", but they are definitely not the same thing. It's just that English uses the same verb phrase for a couple of different meanings and there are many instances of this because English is rather fond of using the same word for an intransitive verb and a transitive verb which is essentially the causative of the intransitive verb.
Kuamka is the intransitive verb "to wake up". The subject is the person who ceases sleeping and begins to be awake. There is no object.
Tutaamka = We will wake up.
Kuamsha is the transitive verb "to wake up". English happens to have one word for both but many languages don't. It essentially means "to cause someone else to wake up". The object is the person who ceases sleeping and begins to be awake. The subject is the person (or thing) that causes that to happen.
Tutawaamsha = We will wake them up
Niliamka. = I woke up.
kuamsha. = I woke
Saying Tutawaamka is ungrammatical in the same way as it's ungrammatical to say "We will die them." "Die" cannot be used with an object. Neither can -amka.