When people speaking different languages came from other lands to meditate, did that ever necessitate speaking the language in which they chanted?
Has there ever been a situation where circumstances necessitated conversation in Pali or Sanskrit?
Yes, though Pali is a "dead language" in the sense that it has no native speakers left to use it, that doesn't mean it can't be used to communicate with others. I remember Professor Gombrich mentioning that it got used to communicate by monks who did not have any other common language.
You can also find examples mentioned in this thread: can people who are pali experts converse in it? in posts by "James the Giant" and "cooran".