I believe there was indeed some research done in the past in which multi-lingual people would generally recover better from strokes compared to people knowing only a single language.

Perhaps additional "connections" are made in the brain that can be used when other "connections" are broken due to stroke.

Anecdotic-ally, my father also recovered quite well from his stroke and he knew Dutch, English and likely a bit of latin languages as well (had Italian and Chinese penfriends when he was young, often used Latin proverbs, ...).