Like in many wealthy American households of the time, it's the lady of the house who is in charge of the servants. Mrs. Lowell is fair and smart, running her house like a business. Margery Cabot Edwards, on the other hand, is a snobby, spoiled rich girl, more than happy to treat all of her household help like dirt. But her maltreatment is a catalyst to get Ceilidh to find work elsewhere, with the Lowells.
No matter how bad your review is, it will still be listed on your reviewer page on Amazon (yes, they exist; just click on a reviewer's name). This is a small spreading of news/linking back, and it will be helpful—almost no matter what you say. Almost.
Because this is not a negative review, you can add some length to it. But because it's not unremittingly positive, it does not have to be lengthy. The ideal length is probably about 50 to 100 words. If you want to say more, contact the writer in private. For self-published works, editing and republishing are usually pretty easy. Hence if you find a glaring translation error, the writer can fix it. You can save the day with your review.