To confirm is it this user preference setting thatvis causing the issue?
As I do not see Trust kevels as options
The Customization > Theme component I linked for I don’t think gives users options to select different Trust Level groups for flairs.
After a quick look at your Op statement and the Custom TL flairs Theme Component. I think it might work best as it adds an additional flair to the user profile; leaving the choice of flairs intact for other group flairs. I imagine you will need to remove how you added flairs to TL and add them to the component linked above. This would likely be the easiest route atm with less work involved.
I think I maybe misunderstanding what the issue is your experiencing. My apologies.