You have done a fine job of sorting through the various issues that this pages presents. I do have a couple of concerns and suggestions to address those.
On the monkey (Canta) item, please note that there is a clear difference between a picture description and a picture caption. The monkey picture has no captions and therefore must be described in a transcriber's note. The colons that you have do not belong there. Colons are part of the format used for captions. So, the TN here should read like a TN, which are the transcriber's words added to the text. The description needs to be clear enough for someone who can't see the page. Your description, two monkeys jumping and two monkeys sitting is fine for someone who can see the page. But this does not tell the blind reader WHICH monkeys are sitting and WHICH monkeys are jumping. It does not even tell the reader how many monkeys there are. I would describe this by saying that there are four pictures of a monkey. The first and third pictures show the monkey jumping and the second and fourth pictures show the monkey sitting. No colons. Keep the TN indicators.
On the Aprende item, I note that you have handled the caption correctly. The purpose of the colon is to make it very clear to the reader that this is a caption of words PRESENT IN PRINT. That is why the colon is so important. No TN indicators here, which is correct, because this is not a transcriber's note. The description follows as a TN with indicators. That's a great description that I'm sure the reader will find helpful.
On the Escucha item--This is a tricky formatting situation that you have handled very well. However, I am concerned about the English picture words on the same line as you have. The English words are NOT in the print and are, in fact, added by the transcriber. That makes them transcriber's notes, which you have correctly enclosed in TN indicators. However, there it NO provision anywhere for a TN to be located any place other than 7-5. Therefore, these TN's CANNOT be on the same line. I would place the TN's on the next line in 7-5.