There is a section for beta languages, but they do not have a label. When you first open the language, it will warn that it is still in beta. They included a package for mandarin in which it matches pairs of words that mostly exists in the dictionary and possible combined words as well.
Every word/lingq is manually made from our side in which it works with one of the translators/dictionary that the respective user has chosen, google translate in most cases.
A solution could be to record all user’s lingqs or have someone go through the app and create a list of words that are confirmed by vietnamese natives and it will show up as a known new word if haven’t been discovered yet.
But in the end, it’s up to them on how they want to approach this language if they decide to further develop it. For now, content is their goal