Boni, that looks like a screencap of a figures library, which should be alphabetical order. Runtimes that get added get listed in order of addition, but in our libraries (figure, pose, etc) the folders are alphabetical.

However, I remember reading something about Macs and Runtime sorting order over at the Smith Micro forums, something about the way they list things has changed. I don't know if this has anything to do with your scenario, but you can see the posts I'm referring to here (specifically by anomalaus and bagginsbill).

https://forum.smithmicro.com/topic/9091/python-method-to-add-a-runtime-folder-to-library/11#