Digital edition of
https://en.wikipedia.org/wiki/Calon_L%C3%A2n with
lyrics in Cymraeg (Welsh) by Daniel “Gwyrosydd”
James (using a standard text variation in verse 3),
composed (on Gwyrosydd’s request) by the Welshman
named Landore John Hughes (usually shortened to John
Hughes; Landore is where he hails from, not part of the
name), not to be confused with the Welshman named John
Hughes who composed Cwm Rhondda, nor with the Welshman
named John Ceiriog Hughes (born John Hughes) who wrote
A...(+)
Digital edition of
https://en.wikipedia.org/wiki/Calon_L%C3%A2n with
lyrics in Cymraeg (Welsh) by Daniel “Gwyrosydd”
James (using a standard text variation in verse 3),
composed (on Gwyrosydd’s request) by the Welshman
named Landore John Hughes (usually shortened to John
Hughes; Landore is where he hails from, not part of the
name), not to be confused with the Welshman named John
Hughes who composed Cwm Rhondda, nor with the Welshman
named John Ceiriog Hughes (born John Hughes) who wrote
Ar Hyd y Nos.
This edition comes with a Welsh pronunication guide for
German native speakers.
Diese Ausgabe enthält eine walisische Aussprachehilfe
für Deutschsprachige.
The [i Gymry] part contains just the Welsh (Cymraeg)
lyrics, without that pronunication guide. Download:
http://www.mirbsd.org/music/free/Hughes%20--%20Calon%20
L%C3%A2n%20%5Bi%20Gymry%5D.pdf
It also contains machine translations (sorry!
improvements welcome) of the footer and other
accompanying meta text.
Copyfree Ⓕ This score is published under CC0
(except that § 2 does not apply (except in the
case of § 3 Satz 2 UrhG or similar) because
licensor cannot legally waive copyright):
https://creativecommons.org/publicdomain/zero/1.0/legal
code
MuseScore version:
http://www.mirbsd.org/music/free/Hughes%20--%20Calon%20
L%C3%A2n.mscx
Also online at:
https://musescore.com/mirabilos/calon-lan
mirabilos, mirabilos 
SHEET MUSIC