We've cruised both the Mediterranean and the Baltic in recent years and have never had much of a language problem in any of the ports...
Of course, in some ports it was probably of great help that we were on shore excursions (St. Petersburg and Athens, most noatably)...that way, with an English speaking guide, there weren't many issues...
But, surprisingly, in places like Tallinn, Estonia - which we did on our own - and Gdansk, Poland - where the afternoon was on our own - and Santorini and Corfu, Greece - where we did only morning half day tours and wandered the afternoons on our own, we NEVER had any kind of problem...
It seems so many people in Europe speak English...and, in the more touristy ports, and especially when doing the typical tourist things, the people you will need to speak with are so dependent on English speaking tourists that English is a necessity...
IOW, don't worry at all...Don't even bother with one of those translation devices...they have limited vocabularies and by the time you type in what you want, you could have just asked in English...
