I'm sorry that you are experiencing issues with the screen printed text on your synths. It's uncommon that we hear of this.
The Prophet 6's steel enclosure is powder coated and then screen printed. The screen printing inks are a two-part epoxy ink so that it bonds and is durable. The inks are cured in an oven after application. So, the finish is robust, but of course not bullet-proof. It is still paint, and as such as susceptible to wear.
Please contact us directly though our dedicated support channel if you are experiencing issues with the finish on your synth: support (at) davesmithinstruments (dot) com.