I ran into that issue last year when I was putting my T/A together.
My lines were leaking like crazy at the carbs, and nothing seemed to help, until my engine builder told me to put some grease on the threads before installing the lines. I never thought that would work, but was running out of ideas.
Greased the threads up with red grease, installed and tightened them, fired up the engine, and dry as a bone!
Grease or oil is best and should always be used on flare fittings to allow you to get them tight.
IMO never use teflon tape anywhere on a fuel system, never. Because it is near impossible to get all the little pieces out when you take it apart. Plus it looks like sh!t and tells everyone you don't understand flare fittings.
I tried thread greasing on my six pack lines, still had 2 fitting that leaked. Perhaps fittings are a bit worn as must undo them each time I wish to remove carbs. Any six pack owner understands this dilemma. Teflon tape relieved immediately.
Have never a problem easily removing it.
As I happen to use an use an air cleaner, impossible to see any teflon tape on fittings.
Leaking fuel lines are a more certain sign that someone does not know what they are they are doing,,,,not to mention the risk of burning the vehicle down.
To each their own
