Hymn No. 27. Praise to the Man -- 166. Clod Fo i'r Dyn

Hymn No. 2. The Spirit of God -- 519. Fel Tân yn Cynhesu Mae Ysbryd yr Arglwydd!

And some would say this is "The Mormon Hymn" as the Saints first sang it at the Kirtland Temple Dedication in 1836 and at many temple dedications thereafter.

Hymn No. 7. Israel, Israel, God is Calling -- 225. Tyred, Tyred i'r DDiangfa

I think this is the right match. The translation is not real close but it's on the same theme and mentions Babylon. It fits the meter and notes of the piece in English.

Hymn No. 292. O My Father -- 523. O Fy Nhad

Some consider this the Great Mormon Hymn. The poem was written by Eliza R. Snow. It was early and popular as it has continued, expressing LDS belief in a Mother in Heaven. I'm glad it was in the Welsh Hymnal of 1852.

Hymn No. 30. Come, Come, Ye Saints -- 221. Dewch, Dewch, O Saint

The words in Welsh are somewhat different. It is more of an "Oh, farewell, oh, farewell" to the old land of violence and evil for a better country of "Saints of pure hearts."

Hymn No. 11. What Was Witnessed in the Heavens? -- 2. Beth a Welwyd yn y Nefoedd

Hymn No. 1 - The Morning Breaks - Cymraeg 1 Y Boreu DDaeth

At first I thought this might be easier as Hymn No. 1 in the LDS Welsh Hymnal of 1852 is the same in the modern English version and the same as the 1851 LDS Manchester Hymnal. And there the similarities end. So this will require some work as I go.