If it’s accurate to official animation it’s accurate to official animation. If we use the one tag for every show I don’t really see that Pony Life should be different – and as Derpy Whooves said, juggling a show accurate tag for every show there’s been or will be would be too difficult to realistically handle with success.
The easiest way to sort this particular issue would, strictly in theory, to just search for “show accurate, [desired show/movie]”. Of course, that would require a comprehensive tag for Friendship is Magic, which… won’t really be happening anytime soon. For the time being, just using “show accurate, -pony life” should probably work fine.