I am doing a graphic for local Easter Rising Commemorations, and would like a translation of exactly that:

"Easter Rising Commemorations"

'Comóradh Éirí Amach na Cásca'

Focloir.ie gives the following example for the plural, "commemorations":

"it tied in well with the 1916 commemorations" bhí sé ag teacht go maith le comóradh 1916

This uses the singular comóradh which would align with Errigal's suggestion above, however, it is in a genitive construction. A better reverse translation might be "it tied in well with commemoration of 1916". I wonder, if the plural is important in this case, would it be better to pluralise it:

Comóraidh Éirí Amach na Cásca

Comóradh has no plural in Irish. No dictionary lists one. It is certainly not comóraidh. If you look at words like samhradh, you will see plurals samhraí and samhraíocha. But I think this word has to be singular in Irish. [I'm ignoring the fact here that the Easter Uprising was opposed by the people of Dublin in 1916, and the commemoration openly glorifies terrorism and so is not worth celebrating.]

Comóradh is originally a verbal noun (verb: comóir).
Its plural, if there is one, would be rather comórthaí.

The only thing I can find in terms of the English plural on the matter is in Foclóir:

centenary celebrations > comóradh céad bliain (singular in Irish)

Also, "ceilliúradh" is used for many other examples there, many of them being the plural in English, but the singular (at least FORM) in Irish.

Yes. If comórthaí is attested as a pl, as Labhrás said, it may refer to commemorations of various different events, as "celebrations" in English often refers to a single event (e.g. a celebration can be up and down the country, and so there will be many venues for the celebration of a single thing).

Fair points.