I doubt anyone would disagree "the world's foremost authorities" on classical lit need to know greek/latin.
But carefully reading and comparing several translations while following centuries of commentary can surely make one an expert on, say, themes in Greek epic poetry. I mean, if it doesn't then I'd just want to introduce into our conversation a distinction or two in the area of "knowledge use" and just stipulate which branch I'm intending by "expert"...
(This doesn't really matter for the previous point, but I actually think this just follows from agreeing with you and then taking even more seriously "how much interpretation happens".)
But carefully reading and comparing several translations while following centuries of commentary can surely make one an expert on, say, themes in Greek epic poetry. I mean, if it doesn't then I'd just want to introduce into our conversation a distinction or two in the area of "knowledge use" and just stipulate which branch I'm intending by "expert"...
(This doesn't really matter for the previous point, but I actually think this just follows from agreeing with you and then taking even more seriously "how much interpretation happens".)