As a mobile app user I miss a critical feature that reduces user experience friction.
That feature consists on having a smart scroll bar that allows to see at a glance all the elements of a table of contents and jump.
Currently, you just have a row page, for which you have to scroll manually to find content. This can be horrible for long documents.
Have a smart scroll bar like Google Docs app to have an eagle view of what the user is currently seeing in a page when scrolling.