You seem to be struggling with your approach, so perhaps you might like to try something different?
I re-worked @Kevinkun 's cardview example here which shows a first level of data (taglist), then on selecting a card, shows the second level of data (content of tag). This all happens on one screen, no need for multiple screens. Not tested with big data, so the blocks may need some modifying for the "load 20 records at a time" feature to work properly. I aimed to use the same firebase structure that you have shown, but obviously using different content, for this example.
Firebase Data:
Blocks:
Video:
AIA (you will need to add your own firebase url and ProjectBucket):
FBTwoScreensCardView.aia (84.9 KB)
Credits @Kevinkun for the CompCreator extension and cardview example
Credits @ ColinTree for the ScrollHandler extension
Credits @Ken for the Click extension
Credits @gordonlu310 for the Beautify extension