Both of my grandparents' marriages involved 2 languages. English with French and English with Serbo-Croat. How did they deal with things when they were cross and couldn't think straight? It's impossible enough with the same language.
There were religious crosses (!) too, Catholic and Church of England, Serbian Orthodox and Church of England. They were called 'mixed marriages' then.
Both my grandmothers went back to their families to have their first children and have them baptised presumably. Their birth stories weren't encouraging though!
Not even an aspirin for my mother's birth, though there was a midwife sitting there knitting in Fontainebleau, as my French grandmother pointed out to me bitterly. She had her second child in the UK after that experience.
In my Serbian grandmother's case she took the decision to have all the drugs in New York for the next 3 children. So that tells me quite enough about her first birth with my father in Belgrade.