I typically use for spanish antiphons gabc transcription tool https://bbloomf.github.io/jgabc/transcriber.html. Although it technically doesnt have a spanish option, you can still paste in spanish symbols and accents. Typically I select English as the language then past the spanish I want to use. Putting dashes between notes helps the program to recognize where to split vowels. When I have problems, I manually do it by using the "show intergrated GABC" tool. Then, I edit it how I want it on the paper with source and summit editor.

Here are some examples

Forum member @smvanroode did the typesetting for SEP. From the frontmatter:

Chant engravings done in Gregorio (http://home.gna.org/gregorio/)
This book was engraved, typeset and designed by Steven van Roode, Breda, the Netherlands.

If you're planning to make a complete publication like SEP, that is probably your best route.

If you're producing things more sporadically, you can achieve passable results pasting the chat scores as vector graphic files into a Word document, then formatting the verse text how you like.

@RichardMix Yes, its not the best, but until a Spanish friendly transcription arrives, its all I got.

@chonak, I was told my Spanish Speakers that this practice is good in hymns but not good in gregorian (to be avoided).