They're in the 1996 Bible and 2009 Presbyterian Hymnal. In order to print those texts, the church uses inline JPGs or Private Use Area codes with special fonts.
There's more in the Hakka Bible and hymnal, which I plan to study more this weekend.
Is this an area you work in or is it a hobby project?
http://unicodepowersymbol.com/we-did-it-how-a-comment-on-hac...
https://www.unicode.org/L2/L2017/17204-uax45-additions.pdf
They also need a font. I tried to find the original, but in the end just asked Andrew West from BabelStone Han to redraw the characters for me.
It's a hobby project. Finding characters was a side effect of trying to scrape data for Pingtype https://pingtype.github.io (my Chinese learning program). When I tried to scrape characters from the Taiwanese Bible, I found inline JPGs and thought "that can't be right..." which led me down a rabbit hole ending here, exchanging emails with Richard Cook, Ken Lunde and John Jenkins (the world experts).
http://www.lingshyang.com/bible/taiwan_Bible/2ch/2ch14.htm
If you have access to a Chinese-language paper library, please try to help take photos of some characters. Search "please contact" on the BabelStone list for some urgent ones. For example, "U+F2DD Alternative character for Db (Dubnium)" and "U+F2E2 Alternative character for Rf (Rutherfordium)" could be easily found on a periodic table, I guess.