"A cat is sitting on that chair."
Translation:उस कुर्सी पर बिल्ली बैठी है।
No because in Hindi sitting and standing are action verbs not stative verbs- think of it like sitting down and standing up. Therefore you're actually using the present perfect in these sentences (literally, the cat has sat down). बैठ रही है would mean "the cat is sitting down" (that is, in the process of sitting)
In some cases we are marked wrong as we put the most logical English translation i.e This car is mine - Yeh meri gadi hai', and here it is marked wrong as they decide to not do direct translation but logical English. Please keep the sentence structure rules consistent, if possible. Otherwise it is very confusing for the learner.