‘Níth naoi n-aoi’, ní ‘Nigh ní naí’
‘A nine guest battle’, not ‘Clean an infant’s thing’
There's an article in the Irish Times a new book subtitled "Foclóir Comhfhoghar Gaeilge – An Irish Homophone Dictionary"
It has "200 pages, 1,000 headwords, 2,000 homophonic sentences", and there's a dozen or so examples from the book in the article. Obviously some of them rely on some obscure or maybe archaic constructions but some of them use words that you can look up in FGB, and at least one example works with Duolingo vocabulary (though it either uses an odd dialect, or the IT sub-editors have slipped up again).
Deinim deinim den im - "I make denim from the butter"
(I would expect déanaim, rather than Deinim, and deinim is an obvious loanword).
This one goes beyond Duolingo vocab, but it is actually pretty straightforward - except for the Irish spelling for Louis :-)
Luaigh Lughaidh luaith luaidhe - "Louis mentioned leaden ashes"
Dein is used in Munster instead of déan. Likewise, the past tense is (do) dhein(eas) instead of (do) rinne(as).
And in Connemara, it's pronounced as if written díon. Likewise, im is pronounced as if written ím in Connemara. So I wonder if this is catered to Munster Irish in general.
Also, it looks like it uses things no longer really found in Irish, such as the vocative plural. And doesn't make any distinction between broad/slender for the most part. And, looking more, I believe they're really stretching and using archaic forms to pick these out. I would wager, from the sentences given, that it's not really relevant to a person wanting to learn Irish as spoken today.
I don't think it'd be useful as a learning tool at all, but I imagine that it would be of interest to some of people on Duolingo who are interested linguistic challenges in general (the kind of people who would appreciate the original working title Ag focáil le focail - a verb that is declined but not defined in the FGB :-)
But even people who have no interest at all in that type of linguistic pursuit, can get a few minutes amusement from the very idea that the Irish phonemes that they are struggling to come to grips with can have such varied application - much as learners of English (and even native English speakers) can be amused by articles about the varied pronunciations of ough.
The author is actually from Leitrim, so probably closer to Ulster Irish than Munster Irish, but I imagine that he had to lean on lots of different dialectic oddities to pull off some of the homophones. And the Munster speaker on Teanglann pronounces im as ím too.