The Courtship of Wyatt's Father - S6-E16
Continuity mistake: When Gideon warns Sara not to use magic to put the books in the library back on the shelves, her arms are at her sides. A second later, the shot changes to over her shoulder as Leo orbs in and she has a nearly full armload of books. (00:08:55)
The Courtship of Wyatt's Father - S6-E16
Continuity mistake: Darklighters are not supposed to die from Darklighter arrows. When Paige and Phoebe get them out of the ghostly plane, a second Darklighter shoots the main one, and he instantly is vanquished. This has never happened to my recollection as DL arrows are meant to only harm Whitelighters or future Whitelighters. (00:35:45)
The Courtship of Wyatt's Father - S6-E16
Continuity mistake: When Leo and the sisters are in the alley with darklighters, Phoebe falls from the roof and her high-heeled boots become flat shoes. (00:14:40)
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.