"– Hello! Who are you? – I am Väinö."
Translation:– Terve! Kuka sinä olet? – Minä olen Väinö.
I wrote Moi, kuka sä oot? Mä oon Väinö which is slang language and marked wrong here. Are you planning to include slang language later? I guess there is both something in favour of it (hardly any Finn says minä olen, right? Only in some formal occasions i guess) and against it (it is good to learn the actual language first before going into slang).
The word moi should already be accepted. Report it, if it's not and we'll add it. As for sä oot we'll probably add regional spoken language forms as alternative translations at some point. I don't know if we'll ever actually teach those though. It's an ongoing debate. :)
We don't really use the formal you in Finland. Maybe if you're addressing the president during Independence Day or during the opening of the Parliament. Some older upper middle class people like being addressed te in service situations. That's about it. In this particular sentence the person who is asked the question answers with their first name rather than a title and a name, so it seems unlikely they would even want to to be addressed with te. :)