Does getting a PhD in a language 'L' from a non-'L' country have any drawback in case of academia?
What kind of problems may he face if he moves to an Anglophonic country to be in the academia?


No matter where he did his Ph.D., he is likely to face an extremely tight job market, with many more extremely qualified job candidates than open tenure-track positions. 

In general, to get hired, it is to his advantage to make himself and his work known to whatever sort of department he hopes will hire him. So, for example, it is a good idea to attend (and speak at) conferences in countries where he intends to apply for jobs. 

It is also a good idea to take steps to "understand" the sorts of universities where one intends to apply. For example, from what I can tell, the "small liberal arts college" model seems to be uncommon outside the United States and Canada. If he were to apply to such jobs, it would be to his advantage to learn in advance about how they operate, and to learn something about what they value.