Languages missing / not syncing to Apple Watch
Unfortunately, on Apple Watches, it takes quite a long time to complete the initial sync with iCloud.
When you first use Wokabulary on your Watch, it can take several minutes until you see any vocabularies. And even then, it can happen that you only see one of your languages because the other have not completed syncing, yet.
So, if you don't see all your languages on your watch initially, please just wait a bit longer for the other languages to also appear on your watch. Especially when you have a lot of words, it can take several minutes.
Tip
Note that syncing continues in the background even after the loading screen disappears. But it is generally faster while Wokabulary is active. When you still miss a language, maybe do a quiz in another language to shorten the waiting. 😉