Again. When searching for projects with a certain tag, use the lower search box where it says Select a tag... The one at the top where it says Search for games or creators only searches titles and short descriptions. And that search is optimized for exact matches, So if you just search for "Godot" it's not going to find much.
And again. When editing your project, go to Metadata and from there pick Engines & Tools. You'll see a field where you can add Godot as an engine. That's something people can search for specifically, and find it more easily than through tags.