Can "A new title is on the book" not be accepted for some reason? It seems right to me...
Except that it isn't "a perfectly acceptable Anglo Irish phrase". You won't find Irish people saying "a new title is on the book" - it's an unnatural construction that sounds "foreign" to Irish ears.
Note that "do be" is not a "literal" translation of bíonn. It's simply a construction used in Hiberno English (not Anglo Irish, a different kettle of fish altogether) to mark the present habitual of "is". It has no relevance in this case.
I agree completely. Every other example of this construction has been very specific about the English translation. While this second option has a more natural sound in English, I've never been able to use it as a correct answer before. It seems to me that Irish is very particular about the differences between subject and object, whereas English isn't quite so picky.
ex 1: "There is a new title..." "Title" is the subject. ex 2: "The book has a..." "The book" is the subject.
Irish eclipsis and lenition, as well as almost every other rule, seem to require precision in subject use.
Thoughts from a native/more experienced speaker?
I wouldn't bother: unlike most other languages, Duolingo hasn't sourced a voice synthesiser for the speech. This means that they've had to use a voice actor to read the line, which is vastly more expensive and time consuming than using voice synthesis.
Some day, the course might be fully voiced, but that won't be any time soon.
I don't think that's necessarily true, mainly because I believe I recall an exercise in this lesson asking for that exactly, but also because "ag" is not always the preposition to use when translating "have" or "at".
I could be wrong, because I'm not a native speaker, but there are instances where the English may use "at" or "have" (but could use "on"), and the Irish uses "ar" (ie. "the roof has paint" would use "ar" in Irish, iirc)
Also, it's useful to keep the (almost) literal translation in mind: "there is a new title on the book". English uses "have" here, but it's not really about possession, but more about something's properties. Irish makes this distinction, English doesn't. It's the very same thing that's done with emotions, &c., in Irish.
In addition, there are also instances where the Irish uses "ar" instead of "ag" where a similar sentiment can be expressed in English also using "on" instead of "at" ie. "they look at the landscape" uses "ar" in Irish, and can also be expressed in English as "they look upon the landscape"