This is a very cool investigation. It inspired me to dig deeper and look through the project files. Allow me to add to your findings:
| Godot | 32 |
| Unity | 32 |
| GameMaker | 7 |
| HTML5 (HTML/JS/CSS. No engine) | 6 |
| GDevelop | 5 |
| Unreal Engine | 2 |
| RPG Maker | 2 |
| PyGame | 2 |
| Ren'Py | 1 |
| Scratch | 1 |
| Raylib | 1 |
| Ink | 1 |
| Love2D | 1 |
| Ebitengine | 1 |
| Electron | 1 |
| SDL3 (Emscripten/WebAssembly) | 1 |