I am living in Norway, Europe, and this is something we in Europe are familiar with. Many languages are spoken here. One of my TB's are in Germany, but most of the logs are done in English. For me German isn't a big problem, but it is certainly several languages i dont understand much of.
It seems that most TB's will be logged in English by those who feel they can enough English to do so, at least when they understands it is a TB form another country.
Many good suggestions for understanding foreign logs are made, but another suggestion is to find a discussion forum for the country with the language you would have some help to understand. Most geocachers will be more then willing to help you out with a translation.
Enjoy your TB's vacation in Europe