Marked as wrong when I chose to put "and best wishes!" even though, in one of the previous phrase, it showed me that "Onnea" alone (as opposed to the full "Paljon onnea") was a correct translation for "Best wishes" and accepted it when I wrote that. Is there a fine nuance to it? Thanks.
Best wishes is a synonym for congratulations in English. Tervetuloa ja onnea translates into "Welcome and good luck" or "Welcome and congratulations". As explained in the comments of Paljon onnea! -exercise (I hope you find that discussion) paljon onnea and onnea alone are slightly different since one is a phrase. Welcome and best wishes sounds a bit weird in English and is probably therefore not a good translation for this.