You are correct, there is not very much on the enotes Study Guide for the novel Twice Blessed by Filipino author Ninotchka Rosca. There’ll be more to come, I’m sure! It actually has more information than a lot of other sources. In the meantime, here are some places you can find more information.
First of all, Wikipedia does have some information. More importantly, it has a series of links you can follow for more information. It also has some background on the author’s life. Here is the link, and it is also below.
I also include a book Review from the LA Times that happens to include a lot of information about the book.
The book even has a Facebook page!