If Magnus offers draw in Norwegian, and Caruana does not understand, then is the draw offer valid?
Valid for what?
If two people are playing a match, there presumably would have been a time before the match when communication and agreement on rules would have been required. The ability to find a common language would be essential
But you ask, what if Magnus had a stroke at the board and lost the ability to communicate in English, he might only be left with Norse- would it be a valid draw offer?
I think so. If there were confusion, an arbiter would be called over. Presumably, there would be communication attempted and someone would realize that Magnus was having a stroke and that an ambulance should be called.
If Magnus offers draw in Norwegian, and Caruana does not understand, then is the draw offer valid?