I've been looking into finally buying the rest of the Adventures books for my sister to read, but Irma's book (Enchanted Music) has next to no information online. A few people on Goodreads and similar book discussion sites have talked about reading it, but there's no indicator that they read the book in English....did the English release of that specific book get cancelled? Even Amazon.uk's listing doesn't have any copies for sale!
.Just to add to MoonCloud's answer:
I've tried to find it too, but with no success. Take my word for it, It's not possible.*
The thing is: This book was going to be released but got cancelled for some reason. That means it has a cover, ISBN, description and all that.....but it doesn't exist.*
Although It's not an incomplete work, you won't find it in English, save your time and buy it in another language. That's what I've done (Portuguese).
*There are indeed some advanced copies for publishers out there, but unless your cousin owns Disney or something, you won't be able to get them........legally.