Local magistrates

[D B Campbell]

Is anyone familiar with these?

Erm, I'll have a go at the Roman ones.

conductor – executive on private estate (or perhaps imperial estate), not government title

Yup, basically a lessee who subleases parcels of land for rent.

defensor – executive on private estate (or perhaps imperial estate), not government title

Basically someone who defends another person in a trial.

duoviri –

Literally, "two men"; these are local magistrates. The Romans were keen on collegiality in high office (two consuls, for example). Singular: duovir or sometimes duumvir.

duoviri quinquennales –

The qualification quinquennales simply means that they were elected every five years.

magister – generic term for magistrate

Yup, magister ("master") covers a multitude of high offices, civil (e.g. magister epistularum, "master of the emperor's correspondence") and military (e.g. magister equitum, "master of the horse").

Those are the Latin ones, at least.