Looks like Aer Lingus will be operating out of the C Concourse at CLE (C14 is what I've heard), will use the United Club for business class passengers, and have their ticket counter next to where Alaska Airlines operates (what was Tackl Health COVID testing).

I bit the bullet and booked a trip in November CLE-DUB-EDI-GLA-DUB-CLE. Looks like they will pause service Jan.9-Feb. 17, 2024, due to aircraft overhauls (also happens to be the depth of the low season). Let's hope they actually restart service again!