4 big but not impossible thoughts
Give the option of adding a field that is a unique ID that can be set to be hidden and/or un-editable, set as the field for linking to other libraries.(not entry name)
Give the option for dropdowns, multiple choice, radio, lists etc to be read from other libraries and give the option for these to be dependent on current library field values.
Give the option for more custom buttons for control of a custom action scripts.
Option to declare global variables that can be accessed by all libraries and global action and trigger scripts that can be utilized by all libraries