For some time I have observed the same problem when making Reading Apps using books created in Bloom. While the Andika font seems to be used everywhere else in the app, the internal Bloom Reader always displays the book text in a different font from the one in the original BloomPUB file (noticeable in the different form of the ‘a’ character). Also, there is sometimes text overflow causing scroll bars to appear even when this is not the case with the source files when viewed in Bloom Reader or BloomPUB Viewer.
I am now able to get correct fonts displaying inside Bloom books. I’m using the latest version of RAB. But in the apps that are created the font size in the books appears a little larger than in the original BloomPUB versions which is still resulting in text overflow and scroll bars on some pages.