Yes, that book. It could be that calamansis are not common in AU at that time, that makes sense. I think I saw it referenced in your recipe. The cilantro remind one of briyani, imho, I don't know if the briyani-likeness would make a difference?

Here's one

https://www.peranakanmuseum.nhb.gov.sg/learn/digital-resourc...

I find it fascinating that the diff is almost only the "source of tartness"!

Thanks!

PS, your story could even make it into that site..