I hadn't heard of exactly that, but in the shape-note hymn singing tradition of the US it was considered sacrilege to use sacred texts in choir practice - you were only supposed to sing them for real. So they developed "fasola", singing all the hymns in sol-fa when they weren't actually in a church service.

I think. There are people here who know far more about that kind of music than I do.

The New Grove article "Notation" includes a sample of sol-fa notation for a hymn from the Church of the Lord Aladura, a Nigerian syncretistic Christian sect. They write their hymns out in a sort of code, with special pronunciations. It doesn't look like any human language but it comes out sounding like one. "Bow down before the King of Glory" is written "BIEURRAR", and a verse of the hymn goes:

  LWWOJJTTAT GORRALLAL ABBULLAL
  SAFFURRA AWWOJLLAL BLLULLAL
  OSSAJJTTAT ALLOLLOL RABBLLAL
  ALLOLLOTTAJJ WOJJTTAT BULLAL
                   BURRAR.

(Text underlay for this, using ABC and representing both the words and the sol-fa, is something of a challenge, which is why I was interested in it).