Ok, so this, as a phrase, is translated “for a year”. But ἐνιαυτὸν means “year, anniversary, any long period of time, cycle, astronomical period” and some of the meanings for ἐπὶ are (with acc., of time) for or during (a certain time), for (a long time); up to, until (a certain time). So shouldn’t it be possible that ἐπὶ ἐνιαυτὸν also means ‘for a cycle’? Or ‘for or during an anniversary’?
A search for ἐπὶ ἐνιαυτὸν in Diogenes shows pages of “for a year”. But since it was translated from the language it was originally written in, is it possible ἐπὶ ἐνιαυτὸν could have those other meanings?
How likely is it?