Why would you need an icon for Hello World? That's like something you boot once to see if you have everything installed correctly lmao. Their is a savine icon (it should be included in the download) and I don't know about colorized cube.
Since you have a thread about icons, let me ask: Where do you get normal game icons? I have two games within my Loadiine and neither of them have an icon. Just a large question mark. The game cover is installed just fine (installed within Loadiine) but still no icon.
You can either A press + to download covers (provided you have the correct titleID in the folder name. Unsure if this also downloads icons) or B make sure you have the meta folder in the game folder alongside content and data. There are certain .XML files that need to be present in order for the correct images to be shown.