Full disclosure, I don't use pod systems. I'm sure folks who do will see this thread soon and help out. I do have a couple of thoughts though for whatever they are worth
Nicotine is the biggest factor in getting TH. Your reduction in nic level will contribute to less of it. I know you said you experienced the same effect with the 18 mg liquid, but I wanted to mention it anyway.
If you are buying filled pods I suspect they have nic salt in them instead of regular nic. Nic salts has less TH. If you can refill the pods with regular nic juice you will probably get more TH, but I don't know how much closer that will get you to acceptable TH over time. All you can do is experiment with it and see if you can find something that will work better for you. There is nothing wrong with staying with more nic while you are quitting smoking. Quitting is IMO much more important than to reduce nic levels.
The other thing is to just vape less often, or for shorter vape sessions, so you don't get acclimatised to the TH as much.
Best of luck with it!