social worker, in some countries (not sure about Canada) is a professional major, i.e. in order to work as a social worker, one need to have a accredited degree.
while public admin in not a professional by itself. It is about politics, and how the public institution administrative. Kind of MBA but in public sector.
An MPA will go through various quantitative method, political theory, and economics for foundation in general, and then some more advanced topics in policy making and etc...
The biggest concern for MPA for OP is not language issue. That is something one can solve.
It is "which government will hire a foreigner to work for her!?"