is this a completed action or an ongoing one, or can it be both?
ie is "she studied the language for one year" ok, or does the case imply that she is still studying now?
This sentence to me is lost in translation. I thought Вчила meant learned and read the sentence as "She learned the/a language in one year." Also, since there's no Ukrainian word in here to say "in" or "for" it further loses me with translation.
The verbs that have to do with knowledge acquisition are complicated in Ukrainian. Because "вчити" is an imperfective verb, it means the action is incomplete. So "study" is a better English approximation because "learn" generally implies that the action is over and the knowledge has been successfully acquired.
To say "in one year," there would have to be the preposition за: Вона вивчила мову за один рік, or She LEARNED (and here I'm using a perfective verb, вивчити) the language IN one year.
Hope this helps.
She has learned the language for one year. - не прийнято. Чи потрібно рапортувати?