Yes, I see your problem.
You see the Icons are smaller than Text because Fusion changed the DPI Scaling (increase to 150% or 200%, up to your Windows version) in your Windows VM if you checked 'Use full resolution for Retina display' option in VM Display settings.
If you think the font size is too large you can uncheck the option 'Automatically adjust user interface size in the virtual machine' (sign-out required) and adjust the DPI Scaling manually in Windows VM-->display settings.
For Windows built-in applications like File Browser, both the Text and Icons can be resized via DPI scaling, but for custom applications it seems only the Text can be resized.
Hopefully it makes sense for you.
mit freundlichen gruessen!
-Rick