hi, just to add, here the construction is analogous to plato's savage attack on the nose of one of socrates' accusers, impossible to forget this sentence, present tense of verb referring to current knowledge:
ἔστι δὲ τῶν δήμων Πιτθεύς, εἴ τινα νῷ ἔχεις Πιτθέα Μέλητον οἷον τετανότριχα καὶ οὐ πάνυ εὐγένειον, ἐπίγρυπον δέ. - Euthyphro 2b
similarly here, in your e.g. the verb is really referring more to knowing (now) by hearsay in the past, e.g. see plato's gorgias 503c at the beginning of plato's attack on pericles and other famous statesmen as flatterers of the mob:
Τί δέ; Θεμιστοκλέα οὐκ ἀκούεις ἄνδρα ἀγαθὸν γεγονότα καὶ Κίμωνα καὶ Μιλτιάδην καὶ Περικλέα ...
see LSJ on this verb, para 2:
2. know by hearsay, ἔξοιδ’ ἀκούων S.OT105: pres. is used like a pf., νῆσός τις Συρίη κικλήσκεται, εἴ που ἀκούεις Od.15.403, cf. 3.193; in Prose, Pl.Grg.503c, Luc. Gall.13.