Apologies for double-posting the previous text. Friedman in "History of Color Photography" in the first two pages of Chapter 26 gives a good discussion of pinatype dyes; he even addresses the 1911 article from Brit. J. Phot. vol. 58. He mentions specifically the natural dye carmine, among other types, and he gives a broad discussion of the chemistry of suitable dyes.

In particular "sulphonic groups", (which I take for "SO3" groups), caused the dye to stay in the gelatin; while "nitro groups" (NO2) caused the dye to wash out easily. It seems likely that many azo dyes with a SO3 group could be good candidates for pinatype dyes.