Custom Icons Not Displaying in Modern UI After Converting a Classic UI Screen

I am converting an existing Classic UI screen to Modern UI in Acumatica and facing an issue with custom icons not displaying in the Modern UI.

In the Classic UI, I have custom icons for the Set Default Site button and the Back toolbar button, along with folder and file icons displayed in the grid. These icons work correctly in the Classic UI.

In the Modern UI, I have configured the button icons using @actionConfig in the TypeScript screen definition, as shown below:

@actionConfig({
    images: {
        normal: "/AcumaticaQMS26R1/Pages/EW/QC/Icons/setdefault.png"
    }
})
sPSetDefaultSite: PXActionState;

Similarly, I have configured the Back button icon using back.png. However, the icons are not displaying as expected in the Modern UI.

The Classic UI also uses CSS classes and the grid_RowDataBound event handler to display folder and file icons in the grid. I would like to understand how to implement the same functionality in Modern UI.

My questions are:

1. What is the correct way to configure custom PNG icons for buttons and toolbar actions in Acumatica Modern UI?
2. What is the recommended way to specify image paths in the TypeScript screen definition?
3. How can I display custom folder and file icons in a Modern UI grid, replacing the Classic UI CSS and grid_RowDataBound implementation?
4. Are there any additional configuration steps or limitations for custom icons in Modern UI?

Any guidance, code examples, or documentation references would be greatly appreciated.

Thank you!