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Zonal
1. When you come across a code chunk "ActivateWindow(1xxxx)" you look up this number in [url=https://kodi.wiki/view/Window_IDs[/url]. In this case, it references "videos" (video library root node, the code of which is in MyVideoNav.xml), so you could have written this as "ActivateWindow(videos)". (Or Videos, case does not matter here. The wiki actually advises you to use the named reference instead of the numerical one, but if you have to write it using Kodi's keyboard (rather than your PC's) you know that inputting numbers is MUCH faster & safer.) So if you get ActivateWindow(Videos,"library://video/anime/",return) this is exactly what you are supposed to be getting.
2. If you get ActivateWindow(Videos,"library://video/anime/",return) and nothing else this means you have not configured your anime node. You have created a root folder "anime" containing nothing but an index.xml. Read this thread top to end for advise.
3. There is no skin that does not provide access to smart playlists. On the other hand, only Confluence-based skins provide an easy way to hack into their code, including access to smart playlists. I have ever used Confluence-based skins (currently Xonfluence, Confluence Extended & Unity), so I wouldn't know how to help you with the skins you mention. Still, I cannot see how skins as accomplished as Amber, Aeon Nox Silvo and Arctic: Zephyr - Reloaded make it difficult for users to access smart playlists.