Are the default parameter values in the reram model accurate for a skywater shuttle? Is there any variation data available for the same? Im trying to select a safe but not too conservative max readout voltage. is there any consensus on what is a good max value for the same ? (my bg: new to analog design)

There is a document cited somewhere above that has a nice graph of measured results vs. the model. The measured results have quite a large amount of spread relative to the model. I would suggest allowing for a good amount of margin, as much as you can tolerate.

would the document be the Hsieh et al. (stanford) multi level cell characterization effort ? https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8993514