Latin sentance, which word is this adj modifying?

Question

Caesari omnia uno tempore erant agena
it means "by caesar every one time (they) had to be done"

which word is omnia modifying? and can you maybe decline that word?

Answer 1

It's not modifying anything - it's a nominative plural noun, subject of the sentence. It's from omne, omnis, a third declension neuter noun. In its plural forms, it means 'all things'.

Assuming 'agena' is a typo for 'agenda', the sentence is:

All things had to be done by Caesar at one time.

Caesar had to do all things at one time. - as an active construction

Caesari is dative, in this case dative of agent, used with the passive periphastic construction. This is often translated as an active construction in English. 'Uno tempore' is in ablative - ablative of time. "Agenda' is the gerundive (future passive participle) in nominative plural neuter, agreeing with 'omnia'.

Declension:
N omne omnia
G omnis omnium
D omni omnibus
A omne omnia
Ab omni omnibus

Answer 2

I believe it's "omnia agena".

Recostruncting the sentence with the English order of words it would sound like "Cesari (by Caesar) uno tempore (every one time) erant (they were) omnia agena".

I suspect that "agena" may be mispelled though.
Perhaps it's "agenda"?

Omnia it the feminime form of the adjective omnius (male) omnia (female) omnium (neutral).