Well, Mr Li's instructions are intended for perforated drums which has less mass and thus can take a bit more initial heat.
Check the MillCityRoasters short video on how to calibrate airflow. Then find three markings on your device.
You're absolutely right about that the heat goes up when you rise the airflow a bit. It's true for most parts except when you're in the latter stages with low heat and high air. The flame is running a bit "rich", so the added air makes the burner more effective. This is why I usually lower the heat before rising the air.

The irratic DeltaBT reading may be due to having the laptop plugged in, not vice-versa. You can try adjusting "Smoothing", about which you can read everything in the excellent documentation made by Susan. (It's in the RESOURSES and possibly Downloads section(s). )

A second tray and fan are used when dropping and cooling the roasted beans.

Thanks for the reply!

Then would I also need a second exhaust bowl to vent outside while cooling ? Or can I just swap the bowl once the beans are dropped ?

I see a lot of people also ordering an extra fan and an extra funnel.

May I ask what are the pros of having those extras ? I don't mind adding them to my list but I just don't want to order stuff that I won't be using.

The roast looks nice, good declining RoR/deltaBT. You're not rushing it. I guess it will taste decent.

Now for critique, I don't know the size of the roast, but you charge way too high. That wil make you hold back on the burner for the rest of the roast. Burner = heat = energy... I.e the beans gets a hefty kiss of energy when charged into the roaster and then they are just kept slowly changing color. If you charge at say 350F (for a 400g - full pound charge), the initial drop of temperture will be much more dramatic. That's nothing to worry about, as it's only virtual. Then (I usually wait one minute) hit the burner at full whack, lots of energy going into the beans. When the beans starts to get yellow, I lower the heat to say 2 kPa, aiming for going into first crack at around 1 kPa. (I don't know if you have tuned your air speed system yet, but I adjust my air to low - mid - high airflow during these three phases, adjusting the heat before adjusting the fan.)
The reason for me wanting to add more energy after charge and towards the middle and later stages of the roast, is that most of the processes in the coffee takes place in those mid and later stages. This is coffee roasting theory, which you will learn while you get experience. Don't worry, you'll get there. Again, as you are new to the Huky, it's impressive to being able to balance the heat the way you did, to produce a nice looking roast.

Nice, I think my image attached anyway, just didn't show in the preview before I posted...