Tłumaczenie - Łacina-Angielski - Omnes Cornelii iam sunt in raeda.

Asterix?

Maybe, raeda seems to be a Gallorum word.

Caro Xini, it seems like homework! (MS Word file).

Just a sugestion

Omnes Cornelii = All Cornelii (V.I.P. of Ancient Rome)

What are Cornelii? Would it be OK to say Corneliuses? Is it a name or a type of status designation?

I found this with a google search, but it still doesn't really answer my question.

In this case, the plural of Cornelius is not formed in the usual way (by adding -es) but has its own special form. So the correct form to use here is Cornelii.

Corneliuses

Yes, Cornelii in Latin
Corneliuses would be an "englishized" version...