The temperature at which specific materials start to break down is known. Manufacturer is irrelevant.
Using cooling fans to regulate cell temp greatly affects performance and provides conditions that are completely different than the conditions that are present when actually using the batteries in a mod. Auxiliary cooling may make things safer for the tester, but it skews any performance or safety data that is collected.
The data collected is certainly worthy of consideration, but the difference in conditions between the test and actual use is pretty drastic and must be noted.
You are right, temperature makes a big difference. Can you describe the conditions inside your mod? It might be interesting to recreate in the lab.