Why my IRA Roth contribution $4200 is excess while I am filing jointly and my spouse does not work and all my annual income is foreign income between 125K > but < 150K?

You must have "compensation" (income from work) to make IRA contributions. Any amounts (other than combat pay) you exclude from income, such as foreign earned income and housing costs, is not considered compensation for IRA purposes.  

Are you using the foreign earned income exclusion?

Excluded foreign-earned income is not income that will support any kind of IRA contribution.