according to: https://cloud.google.com/translate/quotas
google translate rate limits at 6000 requests per minute.
if you are translating on the fly, a busy application would max that out quite quickly. If your content doesn't change that much, you could send a request to google translate when you save your data and then store the translation.
Alternatively you could request it on the fly and cache the response so that if multiple people viewed with the same language then the result would be rendered from cache.