In PVsyst V 5, for historical reasons only the lower tolerance is specified. If positive tolerances, the lower value is set to 0.1 as the 0 value is interpreted as "not defined" and set to 3%.
This value is only used as initial default value for the "Module Quality Loss"
Now the datasheets may change at any time. Many manufacturers who previously defined -3/+3% have recently passed to positive sorting (-0/+3 or +5%).
Rserie and Rshunt are specific parameters of the one-diode model, not specified in the datasheets. In absence of specified values PVsyst chooses default values. See How to fix Rserie and Rshunt parameters?
and their implication in the simulation