I’m not familiar with Ms Keyes arrangements but I Just recently bought several books by JM Staples. They come in graded arrangements. I would suggest a 1 or 2? You can find it at http://www.ldsharpmusic.com

I don’t know if it’s still available but Suzanne Balderston has a book of LDS hymns. Ray Pool has a book titled “Come, Come Ye Saints” in fake book format that’s great. Something to work up to would be the books by Louise Pratt. If you don’t have Hymns Made Easy most of the hymns can be found online at lds.org. Some of the arrangements could be played as written but they also include chords so you can improvise under the melody.

Hands down, my biggest recommendation would be Sylvia Woods Hymns and Wedding Music for All Harps. Many of the hymns in this book are found in the LDS hymn book. The arrangements are fairly easy and include chord symbols for playing with another instrument or for dressing up the arrangement.