There was only one initial tapeout with only basic support for ReRAM. Since that tapeout has not yet come back from manufacture, there is no way to guarantee that the tapeout is successful. However, the ReRAM process has been under development for some time, so there are people who are aware of how it works whether or not the simulation model is correct. The behavior is hysteresis in the I-V curve with an open eye that gives a pretty large margin for error, so a circuit can be designed around the measured I-V curves and can be made to work whether or not a model exists for the ReRAM device.