I have created a way to sort arbitrary arrays in blueprints and stuffed it in a plugin.
Sorting an array with an event:
Sorting an array with a function:
It contains a Sort Array custom node that lets arrays of any type be sorted by an event or a function.
An example project using this plugin can be found here.
Check out the plugin repository for documentation.
This is currently an alpha version. It currently uses a very inefficient sort algorithm that is fine for small arrays but will be very slow on large arrays. I will replace the algorithm when I need it and am satisfied with the approach this plugin takes.
This plugin is free and available under the MIT open-source license. Do what you want with it.