FWIW the flare degree was probably fine, but the nut was not deep enough on the JIC to seal things up. Overall I got super frustrated with all of the different plumbing fittings, acronyms, slang names, and lack of availability on fittings. Particularly converting different types/sizes, and needing them to swivel.
Flare/compression seems like the way to go with this stuff, so you can keep the line in place, and tighten the nut to secure the fittings without having to twist the lines.