Just to let you know, we are finally following in your footsteps with a few tweaks that you yourself recommended.
We'll fly straight to Manchester, avoiding the problem you encountered, and we will catch the train south to Liverpool.

Afterwards we're flying to Westport, and we'll make it in time for a few days of the Westport BlueGrass Festival. Getting lodging there was a bit tough--Fri and Saturday were booked to the max--but I kept checking back and we're good.
We won't be going to Galway and further south afterwards, but we will explore the Trad music scene in Clifton before we fly back to Liverpool/Manchester (we want to explore Manchester too) and home.

Thank you for your insights!

To be really very pedantic from Manchester Airport you will be going (just!) north to Liverpool not south. But in reality it's primarily west.

Absolutely true, John.
It's just in that in our minds, it was north.

BTW, pedantic qualities are always fine by us.

That's absolutely true, John. It's an inland thing versus a coast thing, and I think it's a fact that is important to point out.
No matter what, the train connections are brilliant for our needs. We are excited to see both Manchester and Liverpool. Big football fans from way back.