I have learned a great deal about language from reading your messages.  I have a better understanding as to why it is so difficult for people, like my child and husband, who have language processing disorders.  I am from southwest Louisiana, and I am a Cajun.  I am bilingual also.  I learned French and English together.  Although the French we speak is an archaic dialect of 17th century French.  We have also incorporated Spanish and Indian words into our language.  What makes the Cajun language a challenge is the fact that different areas may use a different word for the same thing.  I may use one word for towel, but 15 miles south of where I live, in Arnauldville, for example, another word might be used for towel.  Therefore, the French spoken in the prairie regions is a completely different language than the French spoken in the river land regions that are farther south and east of  here. 
I thing that one of the reasons people have a hard time with English, or any language for that matter, is due to the
cultural diversity of a country.  Each country adds or corrupts words which become part of the lexicon.  A text book version of a language is vastly different from the language that is spoken by the population of a country.  Indeed, when I taught English at the local high school, I had a hard time understanding the African American students.  They spoke a language that is now called Ebonics.  They used the infinitive form of the verb to be
rather than the proper present progressive form:  I be going to the store instead of I am going to the store.
The English many of them spoke is a completely different language than standard American English.  Actually, I guess it would be considered a substandard language.
I don't know if this will mean anything, but I just wanted to share my thoughts with the group.
Karen Rougeau