Robuta

https://saiveda.net/en/rccs.html
RCCS (Roman Coloured Coding Script) is a visual and intuitive aid in roman script to represent the rhythm, notes, sounds, pauses and sandhi in the Vedas. It...
the vedasdiacritical marksrccscodingcolours
https://tug.org/pipermail/xetex/2010-September/017922.html
combining diacritical marksxetexmisplaced
https://tug.org/pipermail/xetex/2004-August/000675.html
combining diacritical marksxetexmisplaced