To see more of the filter UI:
- use the vertical scroll bar at the right of the Filters panel, or
- change the height of the Timeline.
Here are some documentation links:
The link to the User Guide is at the top of this page (if your browser is wide enough), on the Shotcut - How To Articles page, which is available through the first item in the Help menu in the app (F1).
Keyframes are explained in the documentation and the Shotcut - Tutorial Videos page, which is also a link at the top of this page and in the help menu of the app. Moreover, the tutorials and How-To articles pages link to each other!
There is already a lot, not hidden, and placed in various obvious places to look.