I'd say both Victoria and Viktoriia should be accepted (the first one is just an English equivalent, the second one is transliteration), but Viktoriya is wrong according to this table, "ya" is used only at the beginning of words.
I'd still prefer the more usual "Victoria", I have this problem too, my name is spelled as "Mariia" and I'd prefer people not concentrating on this too much and treating it just as plain old "Maria" :)
"Vybachte, vy Viktoriya?" is accepted.
Side note: unfortunately we have no idea what transliteration is correct because this is implemented by the Duolingo itself, not the UkrDuo team. A lot of transliteration gives a "You have a typo" error for no reason (for example, "Tak, dim tam" for "Так, дім там" says there's a typo in every word which is incomprehensible).