I’m not aware of any relationship in FL coding that could output a defined bank angle, I believe it’s in place to control and damp the bank angle and re centre the ship vertically after the turn.
I think someone on Starport did create a patch for allowing roll control in the FL flight controls but I can’t remember who I’m afraid 😞
Try this link
http://the-starport.net/modules/news/article.php?storyid=142&keywords=roll+control
If you don’t have a high enough figure the ship could topple over or oscillate about vertical, at best I’d suggest trying some different figures in Y axis (roll) and note the effect it has.
Remember mass (and also linear drag) will have an impact here too, so a heavier ship (VHF) will behave differently to an LF in that changing these figures may not have such a marked effect