The Hymnbook, Presbyterian Church in the United States, 1955:

Under "Traditional, Welsh" it lists

#58   Ar Hyd Y Nos/God, That Medest Earth and Heaven
#85   Joanna/Immortal, Invisible, God Only Wise
#197 Arpon/Throned Upon the Awful Tree
#231 Llangloffan/Rejoice, Rejoice, Believers
#333 Llangloffan/O Brothers, Lift Your Voices (same Welsh name as the other one)
#356 Blaenhafren/We Are Living, We Are Dwelling
#511 Llangloffan/O God of Earth and Altar
#517 Rhuddlan/Judge Eternal, Throned in Splendor


Herself says she thinks there are more, and will look after supper.