Re: sealant on brake line fittings
+1
Anti-Seize on the threads only.
Do not contaminate the brake system.
And when tightening the fittings; snug them up and check for leaks.
If you have a leak, tighten a bit more, Do Not crank the life out of the fittings or you WILL have leaks that require the replacement of the lines.
Flared fitting do not require extreme tightening to get them to seal.
Many issues with leaks come from over tightening. Don't get carried away!