Okay, i think i figured this out.
The Arado Ar 234 airfoil (Ar 1.267 20 13-1.1-35/Ar 1.227 20 10-1.1-30) is basically a NACA 12013 (Root) and NACA 12010 (Tip) with modifications to the first digits (theoretical optimum lift coefficient). The last four digits after the dashes are standard German modifications applied to a several dozen of NACA airfoils.
Would like to hear your thoughts on this.