So your wife’s visa says 2-yr residency applies but her daughter’s visa doesn’t say that? If wife is the principal (j-1) and daughter (j-2) it matters. How did she even bring her daughter as an au pair?
if in doubt, follow the correct path to find out if the rule applies.
For 2. That’s something between your wife and the company that got her au pair position. If there’s a contract she signed, look what it says.