Fusion style can't be properly used with Qt Quick Designer

From what I can tell there are 2 parts to the problem. The first is that it seems impossible to set the Controls 2 Style in the Options->Qt Quick->Qt Quick Designer to Fusion. For me only "Default", "Material" and "Universal" show.

This can be (mostly) fixed visually be setting the QT_QUICK_CONTROLS_STYLE environment variable to "fusion". I'm not sure if this works perfectly or not, but so far it's at least a lot closer, and in most cases feels correct.

The second and larger problem is that as soon as the code contains "palette.*" the designer will no longer work. As it then shows an error:
""palette" does not have members. (M17)"
Example to cause this is me setting

palette.buttonText: "red"

This does work perfectly fine runtime.

Optimally I would like to be able to set both the Fusion style, as well as the palette for it regarding Qt Quick Controls 2 in Qt creator. As that would allow what is displayed in the designer to look the exact same way that it looks runtime, but the most problematic part for me currently is the inability to use palette.* and the designer.