Translation:After the dog sees the cat it barks.
Why does "After the dog sees the the cat he barks" not work, clearly it is a masculine noun, even has הוא as "it".
It's correct in Hebrew, but not in English. Grammatically, all dogs are "it" in English, whereas in Hebrew a dog can be "הוא" or "היא" depending on the sex of the dog.
I disagree. I think without knowing the gender most people would revert to masculine. After the dog sees the the cat (he barks/is barking) is a normal sentence and should be accepted.
I think that depends on whether you know the dog - if you call the dog by its name or otherwise know him/her then you would tend to say He/She. If we are saying this about a random dog, I think you would tend to say it.
Yes, exactly, this is extremely common. Sometimes people default to "it" if they simply don't know (perhaps sometimes "he" for some speakers); sometimes they make assumptions or guess; sometimes they ask first (whether it's male or female); sometimes they already know and speak accordingly (e.g., "he" or "she").
People also sometimes use "it" for babies or very young children for some of these very same reasons, although this can be even more flexible for animals (especially certain kinds and contexts where there's less knowledge, more ambiguity, or it's particularly irrelevant). It's simply wrong to say that "he" and "she" are not commonly used for animals in English. Ever heard expressions such as, "Good boy, good boy!" or "Good girl, good girl!"? ;-)
There seem to be many oversimplications, overgeneralizations, and misunderstandings here (in this comment thread). I'm not sure how many are native English speakers, although native-speaker intuitions can often be wrong as well (especially concerning complex linguistic and metalinguistic issues).
I really didn't understand this (English) sentence (but I am not a native speaker...) Can someone expain me it, please?
The disagreement is why didn't duo accept "he" for dog, as in he barks, and only accepted "it."
If you are referring to the sentence, the dog sees a cat and then he/it (the dog) barks.
In English, some people use "he" or "she" for pets, others use "it". Some people will only use "it" if it is a pet (cat, dog, etc.) that they don't know if it is a boy or a girl (like fish or snakes, or if it's not their pet...they are more likely to be called "it") Either is ok.
So, in English you may mix present with past like this? To me it would sound better to say: After the dog saw the cat he/it barked, or, if present: When the dog sees the cat he/it barks.
Yes the sentence is fine, because you a describing events in an order. But I wouldn't say that they were past mixed with present, I don't remember the tense names to be honest, but the sentence is perfectly fine in English.
(Both of your examples are fine too).