Yeh, I thought Rh would be the correct spelling, except I wouldn't call it Welshified as it would be the original. Anything else would be Anglicized. Also, it wouldn't undergo the soft mutation all that often because Rh and Ll are exceptions to a lot of the mutation rules.

I actually do pronounce the 'h' in both speech and in song... sort of a soft flutter of the R just behind the front teeth.

sian