Why is it "a" veranda in this case whether in all previous sentences it was "the" chair, "the" floor... I'm a little confused...
Could this also mean painting a picture of a veranda?
The translation is not grammatically correct in English. You cannot really be painting "a veranda" (abstract veranda). Should be either "the veranda" or better yet, also accept "veranda" as correct.
You can say of course ¨I am painting a veranda¨, if, for example, you work as a painter and your sister calls you asking what you are doing.
Unless you're painting a picture of a veranda. Then it makes grammatical sense. Can maalaan be used for that?
Maalata can be used for art painting, but this section is about house parts and repairs, I believe, not about hobbies. This really should be “the veranda” here. Or should at least be accepted, if still isn’t.
Whi is ¨I paint the veranda¨ not accepted?
My understanding is that this would be “maalaan verannan”. The use of partitive indicates an ongoing process.
The word list says veranda or porch.
But... A veranda is made of glass ! You can't paint it !
No, not necessarily. It can have zero glass, in fact. But even if there is glass, there are also structural elements that are typically wood, that can totally be painted.