Regarding the actual dative form in Corca Dhuibhne:
For adjectives it doesn't exist outside of certain very well known phrases and even they are few and far between.
For nouns it's confined to bróg, cos, lámh, cloch. There are some nouns where it's used in a phrase like fén ngréin or le bróin, although even many of these phrases are falling out of use. Older speakers tend to use it with -óg words, however it's also the case these speakers just use the dative even in the nominative for these words.

Regarding lenition and eclipses, in Corca Dhuibhne you basically always use eclipses:
don bhfear
go dtí an dtigh
ar an ndoras

The adjective gets treated as it would in the nominative.

The only real exception is "sa" which eclipses b,f and lenites other consonants. If it lenites a masculine noun, the adjective gets lenited as well:
sa chuan mhór

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The dialect I use is Cork Irish.
Ar sgáth a chéile a mhairid na daoine, lag agus láidir, uasal is íseal

Go raibh míle maith agat, that information is incredibly helpful.



Regarding this, just to confirm, if doesn't lenite the noun the adjective remains unchanged i.e. sa rang mór?



I have picked up a copy of GCD and it is indeed phenomonally thorough and insightful

It would be incredible if the Irish government saw sense and announced tomorrow that the Christian Brothers' Grammar was being retired, and that the new "Standard Irish" was indeed everything in Gaeilge Chorca Dhuíbhne.

I'll have to get a copy of that, too.

Perhaps had I known of it from the start, I would have studied Kerry Irish all along.

As for Galway Irish, may the information on Iorras Aithneach is similarly comprehensive? See https://www.dias.ie/celt/celt-publicati ... ty-galway/

Sorry for the late reply.

Actually lenition would still occur even without the noun being lenited:

san oileán mhór

Technically there is the edge cases where "sa" eclipses and there the adjective would not be lenited. However in actual speech that's quite rare outside of feminine nouns.

I would strongly recommend a copy of "An Teanga Bheo: Gaeilge Chorca Dhuibhne" and try tuning into An Saol Ó Dheas. The grammar used by actual native speakers is in many cases simpler than what you'll meet with in textbooks, but also with many constructions not mentioned in most texts.

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The dialect I use is Cork Irish.
Ar sgáth a chéile a mhairid na daoine, lag agus láidir, uasal is íseal

And: san am gcéanna and ar an gcuma gcéanna, with eclipsis on the adjective.

There's a sale on. Gaeilge Chorca Dhuíbhne is now €28 and not €35 for a limited time: https://shop.dias.ie/product-category/b ... -dialects/