Direction of offset / orientation of a sweep

Hello !

I was too busy the last months to pursue my grasshopper formation, but I'm back on tracks, and especially back with my louvers problem.

I had made last year something to create quickly louvers on a building. It's been since then reviewed and improved by someone who knows what she's doing.

BUT I still have 2 problems that I want to solve because I don't understand why.

- why after a flip the offset side of the surface doesn't change ?

Generally how to ensure that all my breps will offset outwards the building....?

(I have around 20 of them for the whole building as I have various densities, one brep=one density)

- why some of the louvers always go the wrong way ? It's very time consuming because my boss makes me change them every week and and I have to remove/redraw these one by one...

And for every brep, I have to re-check and re-enter all the louvers dimensions, invert them or put them to negative values, untill most of them are ok on a given brep...

Generally speaking, how to force a sweep to be rotated always in the way we want, without having to change the values to negative...?

Hope someone can give me a direction ! See files attached. Thanks

fanny