Problem with "subtract()"ing "hull()", is this a bug?

For drawing a spherical triangle I need to draw 2 "sp_tria2()"s in that triangle on the sphere. "sp_tria2()" might overshoot sphere triangle borders as here:
Next I create "hull()" from 6 points (found no way to do that, created "hull()" of 6 very small "cube()"s instead), the 3 triangle coordinates, and those coordinates scaled up to that "hull()" completely contains the wanted triangle part of "sp_tria2()":
Here is hull definition:
h = hull( cube({center: sv1, size: 0.01}) ,cube({center: sv2, size: 0.01}) ,cube({center: sv3, size: 0.01}) ,cube({center: s1, size: 0.01}) ,cube({center: s2, size: 0.01}) ,cube({center: s3, size: 0.01}) )
Why does "subtract()" not work when subtracting "h"?
(subtract does work for look_inside=yes, subtracting sphere and cube from outer sphere)
Here is link for you to play with:
https://openjscad.xyz/?uri=https://stammwilbrandt.de/en/forum/Q.JSCAD.vertex_edge2.sp_tria.js... return colorize([0.5,0.5,0.5], subtract( translate([0,0,0], rotate([0,0,la1degToRad(180)], rotate([0,ph1degToRad(90),0], rotate([0,0,al13], sp_tria2(sc, s12, mpi(al13al12), 0.1, 40, 40) ) ) ) ) ), h ) ...
"sp_tria(4,13,14)" call is in line 244 near the end.


Forgot to post the "answer" link for viewing in browser:
https://openjscad.xyz/?uri=https://stammwilbrandt.de/en/forum/A.JSCAD.vertex_edge2.sp_tria.js 
This post is deleted! 
Oops, too late/early, need to get more sleep.
 problem was bad indentation of brackets and placing ",h" at wrong level.
 problem was that I want "intersect()" and not "subtract()":
return colorize([0.5,0.5,0.5], intersect( translate([0,0,0], rotate([0,0,la1degToRad(180)], rotate([0,ph1degToRad(90),0], rotate([0,0,al13], sp_tria2(sc, s12, mpi(al13al12), 0.1, 40, 40) ) ) ) ), h ) )
Works like a charme now: