Why is "The family is still at dinner" is wrong? Why is "still" at the end of the sentence in the English translation?
Yes, according to how it's used, it can also mean 'again'. Ex. " La vogliamo fare ancora questa cena?" Do we want to do this dinner again?
Is there a reason why this sentence could not be "The family is at dinner again?"
To avoid confusion i'd rather say "di nuovo" instead of ancora here. "La famiglia è a cena di nuovo".
p.s.: as for "again" i think "ancora una volta" sounds better
Yes, ancora una volta definitely sounds better, but gramatically it's ok to abbreviate simply with ancora :)
Because by using again in your sentence you would be saying they stopped having dinner and then returned to have dinner another time. While in the sentence "la famiglia e' ancora a cena" it's simply meaning they are STILL having dinner in this exact moment. Yeah it's a bit confusing sometimes...
In English, which one is correct, "at dinner" or "at the dinner"?
"At dinner", unless maybe it's a specific event you are taking about, e.g. at the dinner for John's birthday.
This duo sentence is completely wrong there's no such thing in English grammar !!!!