Replacement for PageLanguage Property in PageData ?

PageLanguages property in PageData is deprecated.
It suggests to use ExistingLanguages property instead of the PageLanguages. 

However, when comes to the filtering, previously the language filtering has been handled by

.Filter(x => !((PageData)(object)x).PageLanguages.MatchCaseInsensitive(lang))

But when used the below,

.Filter(x => !((PageData)(object)x).ExistingLanguages.ToString().MatchCaseInsensitive(lang))

it gives a different result.

How to get the same result as before by using the ExistingLanguages property (or from other property)? Thanks in advance.

Note: I am working on EPiServer.Find.Cms --> 12.7.1.0  ,   CMS ---> 11.5.1.0