I can't understand you

Is Abigail playing up when she ignores Priscilla's questions and remarks, some of which are in Cantonese? When asked why she didn't reply Abi said that she couldn't understand what her mother was saying. Parental fear that she is losing her ability to understand Cantonese, again! Must speak Cantonese whenever possible, maybe have Thursdays (?) as Cantonese only day - is the mother's brain able to sustain it? Will Chris understand?