Maybe it's my English brain, but I keep repeatedly entering, "Let's meet Sunday at the park." Why is this wrong? I feel like if someone said that to me, we'd still hookup at the park at the same time. I'm pretty sure it would be safe to assume I'm not meeting someone named "Sunday" at the park, right?
Mi ne scias
I think it's trying to harp on the difference between "dimanĉon" and "dimanĉe"
If I've got this right, the accusative means on a particular day, on the next Sunday or the last Sunday (depending on the verb tense); the adverb can mean that too, but can also mean any Sunday, or regularly on Sundays.
In English, if I say "let's meet Sunday", I could mean any of those things, and context would sort it out. If I say "let's meet on Sunday", I definitely mean the coming Sunday; if I say "let's meet Sundays", I'm talking about setting up a regular thing.
so I think they're leaning on us to notice the distinction
I don't think this is quite right. You're correct that there is a general (but not always strictly observed) difference between "dimanĉon" and "dimanĉe" - and your summary is pretty close to the truth... but cwsparrow's question was about the difference between "meeting Sunday" and "meeting on Sunday."
I brought this up this morning and I've been told that the alternative translations have been added. It's another case of the alternate translations not being added because this is the new tree.