Hello Vicky,
interesting question - I did not find this in any oficial Release Notes but in an OSS note:
1855398 - Table Personalization enhancements features
The sorting order in Personalization popup is part of it. There is also a PDF document attached to this note, which describes in detail new personalization features, the sorting among others.
These improvements come with SP for the WEBCUIF package as follows:
WEBUI 701 SP11
WEBUI 731 SP08
WEBUI 747 SP01
If I understand correctly your reply, if you are on EhP2 SP6, then WEBCUIF 731 is relevant for you - and you are "only" 2 SPs far from these features then. I am afraid this feature cannot be delivered only via OSS notes but you have to apply relevant Support Package stack (I do not recommend to apply SPs for the WEBCUIF component only).
Hope this helps.
Dawood.