The higher value range for the same satellite product (NO2_OMI_TEMIS)
It seems that you are concerned that your values in the data go above the max value on the color bar shown in the kml file.  I wouldn't worry about that.  You are using the "level 3" monthly average product, which by definition is highly quality controlled.  For most of the globe, typical values will vary between 1 x 10^14 and 5 x 10^15 molec/cm2.  Values over 20 x 10^15 molec/cm2 only occur in highly polluted areas.  Very large values in the OMI NO2 product are realistic, especially in SE Asia, where the largest NO2 columns are obtained.  I have even seen values over 1 x 10^17 on occasion.  As the signal gets larger, there is actually more confidence in the retrieval.  Really it's the low values (e.g. less than 8 x 10^14 molec/cm2) that you should treat cautiously, as anything lower than that could be "noise".  

In order to show the variance of values (which can span 4 orders of magnitude) across the whole globe, the color scale chosen works well.  Note that the color bar is a logarithmic scale, which helps give definition to the plots in the regions with typical values.  You could rewrite the kml file though, and pick a different max value, if you are interested in better plots of southeast Asia.  

If you are interested in learning more about the product, I highly suggest you see Boersma (2011) and also refer to the user manual.