Hi @VasileR, thanks for the fast reply!
I forgot to mention that this is in a component library, which to my knowledge doesn't support UpdateContext?
What I have right now is the following:
A table like this:
Table(
{
HeaderLabelID: 1,
HeaderLabel: "Name",
FillPortion: 3
}, {
HeaderLabelID: 2,
HeaderLabel: "Type",
FillPortion: 1
}, {
HeaderLabelID: 3,
HeaderLabel: "Date",
FillPortion: 1
}, {
HeaderLabelID: 4,
HeaderLabel: "Status",
FillPortion: 1
}
)
Where the FillPortion should make the width. On the label itself I use: Parent.TemplateWidth * ThisItem.FillPortion
With using 20% opacity background I can see that the Name label is indeed 3x the width of the others, but Type is at position X where it would be if Name was only 1x width. It looks as follows:

Type and Date have a darker background because Name is underneath them.