Translation:The last factory is closing down.
"The last factory is closing" is one of the listed translations. Please make sure that there are no typos in your answer. If that is what you wrote exactly and it was still marked wrong, then it's a bug. Could you kindly take a screenshot and post it here if it happens again? With that we can file a bug report and get it corrected.
To me (N. Am.), "to be busy [gerund]" would suggest that there was a particular focus on the activity in question, maybe to the exclusion of all other activities, whereas "to be [present participle]" or "to be in the process of [gerund]" would suggest simply that the activity was currently progressing, and not that there was a particular focus on it or exclusivity to it.
But here's a question for you. The ThoughtCo page about "en train de" gives the following example:
- L'eau est en train de chauffer. — The kettle's on. / The water's heating.
In your variety of English, would it be unremarkable to say "the water's busy heating"? (To me that would be a quirky but interesting way to phrase it.)
Matthew - South African here as well. I agree that "I am busy..." is a fairly natural way to translate "Je suis en train de..." I had no idea this was not an acceptable translation anywhere else in the world. I am guessing that SA English was influenced in this case by Afrikaans, which has the same construction.
In both English and French, the verb ("to close", "fermer") can be transitive or intransitive. Your sentence means "the last factory is being closed (down)". The examples for the following dictionary entry should make it pretty clear: