All of the right weapons on the Nebulon B need to be rotated 10 degrees, and the extra left laser should be 'left laser 10', but is instead a copy of 'left laser 9'
{"bounds":[97,-7.5,60,-16.5,24,-16.5,6,-8.5,-58,-7.5,-60,-26.5,-102,-28.5,-102,24.5,-64,25.5,-57,8.5,8,6.5,20,15.5,60,15.5,97,5.5],"center":[26,100],"collisionRadius":"110","engineSlots":[{"angle":"180","contrailSize":"3","location":[-101,18],"length":"3","width":"6","style":"HIGH_TECH"},{"angle":"180","contrailSize":"3","location":[-101,10],"length":"3","width":"6","style":"HIGH_TECH"},{"angle":"180","contrailSize":"3","location":[-101,0],"length":"3","width":"6","style":"HIGH_TECH"},{"angle":"180","contrailSize":"3","location":[-101,-10],"length":"3","width":"6","style":"HIGH_TECH"},{"angle":"180","contrailSize":"3","location":[-101,-18],"length":"3","width":"6","style":"HIGH_TECH"}],"height":200,"width":53,"hullId":"sw_nebulon_b","hullName":"sw_nebulon_b","hullSize":"DESTROYER","shieldCenter":[0,0],"shieldRadius":"108","spriteName":"graphics/rebel/ships/sw_nebulon_b.png","style":"HIGH_TECH","viewOffset":0,"weaponSlots":[{"angle":"270","arc":"180","id":"right_turbolaser0","locations":[58,-10],"mount":"TURRET","size":"MEDIUM","type":"ENERGY"},{"angle":"270","arc":"180","id":"right_turbolaser1","locations":[36,-10],"mount":"TURRET","size":"MEDIUM","type":"ENERGY"},{"angle":"90","arc":"180","id":"left_turbolaser2","locations":[58,10],"mount":"TURRET","size":"MEDIUM","type":"ENERGY"},{"angle":"90","arc":"180","id":"left_turbolaser3","locations":[36,10],"mount":"TURRET","size":"MEDIUM","type":"ENERGY"},{"angle":"0","arc":"20","id":"fixed_nose_turbolaser4","locations":[76,0],"mount":"HIDDEN","size":"MEDIUM","type":"ENERGY"},{"angle":"300","arc":"180","id":"right_laser5","locations":[70,-7],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"270","arc":"180","id":"right_laser6","locations":[47,-10],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"290","arc":"180","id":"right_laser7","locations":[-70,-21],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"250","arc":"200","id":"right_laser8","locations":[-92,-21],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"60","arc":"180","id":"left_laser9","locations":[70,7],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"90","arc":"180","id":"left_laser10","locations":[47,10],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"70","arc":"180","id":"left_laser11","locations":[-70,21],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},{"angle":"110","arc":"200","id":"left_laser12","locations":[-92,21],"mount":"HIDDEN","size":"SMALL","type":"ENERGY"},
{"angle":"0","arc":"360","id":"launch_bay","locations":[0,0],"mount":"HIDDEN","size":"LARGE","type":"LAUNCH_BAY"}]}
That should be the fixed version - It seems to work well for me.
Note that you need to edit the variant file as well - it lacks a left laser 10.
That should fix the variant file.