-ę eniding is for feminine (and few masculine) nouns ending with -a (Accusative)
-a ending is for masculine nouns ( most, those not ending with -a) - Genitive.
Accusative = Genitive for all masculine "animated" words (persons and animals) , and some other words - and pomidor is one of the exceptions. (I think Many vegetables and fruits are)
That is right (well, more specifically: masculine animate nouns have Accusative identical to Genitive), but actually most natives would treat "pomidor" as grammatically animate. Yeah, Polish is illogical sometimes. See here, part 4,5: https://forum.duolingo.com/comment/28029344
"Ta kobieta je pomidor" is actually accepted, because technically it's a correct answer, but I believe it would sound weird to most natives and it seems likely you'd get corrected if you said that.
I wish it would allow me to type and input English with Slavic grammar order. Like for this one it would be nice if typing "woman is eating tomato" worked. Much faster, more efficient, and it still demonstrates understanding of the grammar, because I'm not learning English. Love it though
There's also such a thing as usus. It's one thing if 'a lot of people say it that way' and another thing if 'almost everyone says it that way'. I don't see any point in teaching you a 'technically correct' version which would, however, almost certainly lead to someone correcting you.
We accept "Kobieta je pomidor", if you really want to stick to it.