Questions about Generator: mesh/objects within spline, snap to control point

[_Aka_]

What is your email address? I can't send them via the email feature in the forum.

I will send you my email address via PM. I am not posting it here because of bots that scrap forum posts and spam found email addresses.
Otherwise, my contacts are in the publisher's page on the asset store: https://assetstore.unity.com/publishers/304

How would I apply a decal on a generated mesh then?

I am not familiar with decals on Unity. I am tempted to say the same way you would do on any other mesh, since generated meshes are just regular meshes

1) When creating road paths, I tried using a generated rectangle as the path, but for some reason, the rectangle is slanted on the vertical, especially when my height value is very small. Is there a way to work around that?

I believe it is because of the "Optimize" option in the Shape Extrusion module, under the Cross tab. Deactivate it and the problem should be fixed.

2) Is there any way I can mirror splines and apply a template I created in Curvy Generator?

There is no mirror tool, but you can select all the control points of the spline and rotate them 180°
If needed, you can change the surface orientation using the Shape Extrusion's Reverse Normal parameter (in the Cross tab) and/or the Volume Mesh's Reverse Tri Order parameter.

Anything else?