This how I would do this:
In Lazarus choose Edit, Search in files and search sccslvedtgrprcaption in the directory lazarus/ideintf.
then I see it is assigned to a caption in line 371 of listviewpropedit.pp
By inspection of the method name I conclude it is part of the ListViewItemsPropertyEditor.
But if you have suggestion, how it can be done better / quicker, please tell.
HTH,
Vincent.