It Add Games Not Existing In My Custom Category
I never play some of these games (print), I checked.They don't exist in my library and some aren't even in the store (eg Tiger Knight empire war)
It is shuffling games from other categories, games from category 1 are also being imported to category 2 for example.

My guess is you have them grouped by library, not by category, Try changing it.

same result is filtered by category only

I don't think there's anything we can do about this. We use Steam's API to fetch list of your games and if that API says that they are in your library then I don't think we can do anything about it. For now you have to hide them (from right-click game menu), proper support for ignore list is coming in future.
Just to make sure, if you use SteamDB's calculator do you see those game there as well (they use the same API AFAIK)?
I my SteamDB's calculator show this!

really!
Total Bug this API, this game (Tiger Knight: Empire War) I never play, never buy, it never be free.
And yet appear in my library when using API
But if it helps,
Import Categories Steam hits 97% accuracy
I'm going to close this then. I don't know why Steam API reports it, but I can do nothing about it. For now you can hide it in your library (via right-click game menu).