You may know already if the nickel strips are steel plate coated with nickel, or pure nickel. THe former have more resistance and lead to more heat build up and have less ampacity. A pure nickel strip can withstand is about 1.5 times that of nickel plated steel. Therefore, when the current is the same, pure nickel generates less heat.
You can test your nickel strips by scratching an area of a small sample, and soaking it overnight in a bit of 10% salt water. When I tested all mine, I found I had one roll that was plated. If the scratched area shows rust, it is nickel plated. (You can use other methods to test such as grinding it with a dremel and if sparks, there is steel in it, or you can measure the resistance of a 10cm strip with a multimeter.)
I see you pre-soldered tabs for the sense leads, and used gaskets for the positive terminals to prevent shorts, good job on that. I did my last pack with single strips like yours, then I ordered a double oblique strip to make the next one easier.
User reviews of the XiaoZiangElectric app have not been too favorable (1.6 on the Apple Store). The 30A model is $20.00 on Ali Express. Perhaps give a JK BMS a try next time.
