They would know about an injury sure, but perhaps not how serious or exactly how long the recovery will be. They would have a good idea but often managers will be cagey about this info in the run up to a match so as to not give away their starting 11.
I think its fine that we don't know. The real problem is the fact he might be losing out on $ because of his opponents failure to have a deep enough squad.
Perhaps a default payment should be calculated and made anyway based on a "phantom match" using all the other usual factors like ticket price and fans etc. With the usual default win ontop.
I know people hate comparing T11 to RL football but im pretty sure if it happens in RL then the club at fault has to pay a fine to their opponent and perhaps even to their FA.