Adobe Illustrator CC start to support Khmer language well beside Arabic and Indic scripts, but you need to check right setting.
Click Paragraph, click drop down menu on the right side. Then tick Middle Eastern & South Asian Single-line Composer or Middle Eastern & South Asian Every-line Composer (See picture).
Click Paragraph, click drop down menu on the right side. Then tick Middle Eastern & South Asian Single-line Composer or Middle Eastern & South Asian Every-line Composer (See picture).
