Use a GC/MS analysis to characterize the [Chinese] fuel.
Well & good to identify spectra for the chemical constituents, but not necessarily a predictor of the behavior of the fuel when uncommon components and unfamiliar proportions are present (if happens to be the case in this instance - which is likely, given the inherent variability of fossil fuels and refinery processing methods.).
Consider the analogy of running a cat through a blender, then running spectra on the resulting goo to see if Sylvester was a good mouser.
There's also the matter of analyzing performance "at temperature" - for the very cold region of interest. Not so easy as putting a coin in a vending machine & having all the answers slide out the chute. Could turn into a full-scale research project to completely characterize the fuel in relevant circumstances. Probably is being done as the clock runs.
One lab test that would be very instructive would be to evaluate the relative frothing propensities of the fuel samples taken, as compared to "normal" JPxx.
Commercially available additives exist to virtually eliminate foaming in aviation fuels. Likewise, additives exist to greatly
amplify fuel frothing and foaming behavior in airborne usage, typically as a method for limiting fire or explosive flame propagation in the event of tank ruptures & punctures - such as might arise from coming too close to a cannon during a military engagement. The possibility that high-grade fuel formulated for military use could become mixed with fuel for commercial use is not too far-fetched. Conceivably the mixing of military and commercial fuel batches might even be a common practice in some places when extreme cold-weather performance is known to be required.